The Kreyol word "mo" (I), which is still used in Louisiana and French Guiana; was used in Ayiti at one time. Do you know when it fell into disuse in Ayiti? Mesi.

I have heard of this CREOLE word 'mo' only because two of my sisters were born in French Guiana (Guyanne Française).  My Mom and Dad lived and worked there for a good three or four years.  I still remember this French Guiana Creole carnival chant "mo le dodo ke to" from when I was five years old.  I am not sure if the spelling is right.  My mom used to chant it too, and  told me that it meant "I want to sleep with you". I am not sure if that's right, because since that time I have never encountered that type of sentence arrangement.  Other than that episode, I have never heard of any Haitians using the word "mo" to mean "I".  My 87 year old Haitian friend just told me that he had never heard it in Haiti (in his lifetime).
If it was ever used in Haiti, my guess would be that it happened during the time when slaves from one plantation (say, Guadeloupe or Martinique) used travel to work in other plantations.  Haiti was the first black republic in Latin America and the Caribbean, it attracted people  in search for freedom and better circumstances.
Anyways, as you already know if we did use it, we don't anymore.

Question for you "Rachal",  How did you come to the knowledge that this word was used on Haiti?  I'd love to know.  Thanks :)

Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words

Choz di choz fèt.....

Choz di choz fèt.....
Thing said thing done....
It happened as they said it would

1. Choz di choz fèt, siklòn nan te vini e li te koze anpil domaj, men tout moun te gentan evakye kanton an.
    It happened as they said it would, the hurricane came and caused a lot of damage, but everyone had already evacuated the area.


Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words

Fè bèk atè?

Non nou p'ap fè bèk atè!
No, we will not back down!

Fè bèk atè → to give up, to back down, to become flaccid (instead of being erected), to chicken out

Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words

How does one translate the probable future tense? "He must have forgotten his appointments." or "He must have missed the plane." or "James must already be in London."

Speculating about a past probability /possibility?
Use that auxiliary verb + perfect tense

1. He must have forgotten his appointments.
     Li dwe te bliye randevou li yo.

2. He must have missed his flight.
     Li dwe te manke vòl la.

3. James must be in London by now.
    James dwe nan Lond kounye a.

4. The juice spilled because you must have not closed the bottle properly.
     Ji a koule paske ou dwe pa't byen  fèmen boutèy la.

5. She missed the concert because she must have been ill.
    Li pa't nan konsè a paske li dwe te malad.

Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words

Mwen se yon granmoun kannay :)

Good for you!  ...but I'm staying away from you :)

Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words

Nou va resevwa ou ak bra "louvri". Is it "ouvri" or "ouvè"?

It can be louvri, ouvri, or ouvè

Nou va resevwa ou ak bra louvri.
We'll welcome you with open arms.

Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words

Would you give me background information on the Kreyol word "genyen"? Is it from the French or West African languages? Also, is it known, at least in some cases, what specific West African language in particular that Africanized Kreyol words come from?

It's from French GAGNER which means TO WIN, TO EARN
GENYEN (GEN, GAN, or GANYEN), in Creole, means to have, to possess, to own, or to win.  Also means there is or there are.  It's also used to ask "What's wrong?", "What's goign on?"
Some examples:
1.  Nou gen twa pitit.
     We have three children.

2.  Mwen genyen yon bagay pou m di w.
     I have something to tell you. 

3. Ekip Eagles la genyen match la jodi a.
    The Eagles team won the match today.

4.  Si'm te genyen lotri a mwen pa ta janm travay.
     If I won the lottery I would never work.

5. Ganyen 2 mil elèv nan lekòl sa a.
    There are 2,000 students in this school. 

6. Sa'w genyen?  Mwen pa gen anyen.
    What's wrong?  Nothing's wrong.

7. Sa k genyen?
     What's going on?

About more than 90% of the Haitian Creole vocabulary words is French. The rest might have come from the indigenous Taïnos (first inhabitants of the islands of Hispaniola, now Haiti and the Dominican Republic), Spanish, portuguese, English, Dutch and others... and of course many West African dialects.  The West African slaves that were brought to Haiti spoke many many dialects.  It is also believed that some of them had spoken another form of Creole that they had learned in Africa.  And also they might have started to speak another form of pidgin language during the voyage to Haiti, as a result of trying to communicate with each other.  It is not specifically known which West African languages had more influence of the Haitian Creole language, but the Creole grammar is often said to resemble the following African languages: Ewe, Yoruba, or Wolof. I think you should keep in mind, also, that many tribes who lived in West Africa during the slave trade to Haiti and the Caribbean islands have either moved, or are probably not in existence as an independent tribe.  So, we might not know all the West African dialects which took a small part in constructing the Creole language.

Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words

Di m Mandaly. "Mwen pa konprann poukisa Bondye renmen nou sa anpil". Se sa yon translasyon korek? Mesi anpil.

Dakò.
Switch the last two words around. And write "konsa" instead of "sa".

"Mwen pa konprann poukisa Bondye renmen nou anpil konsa"
"I don't understand why God loves us so"  You can write  so or so much

Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words

"Bos la la" Eske sa se yon fraz konple?

You're damn right, it is :)

Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words

Yo di maladi damou pa ge renmèd

Adye o! Ki moun ki di sa?
Mwen konn tande yo di maladi damou se pa maladi doktè ka trete. Men, pou sèten, li gen remèd.
Eske ou pa konn tande yo di chak maladi gen remèd pa li?

Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words

Of the two words for "now", (kounye a e koulye a), which is the most used? Mesi.

That depends on what part of Haiti you're from.
Some people say kounye a
Some people say koulye a
Some people sa kounya
Some people say konnya
and sometimes we say kounye a la :)

Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words

Je we bouch pe

yeah.  Don't forget the accent in "wè".

Je wè bouch pe (Eyes see mouth hushed)
You keep whatever you see to yourself
It's an idiom.
Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words

This is a picture of perseverance with learning the Creole language :) Kenbe la Phil! Always love to hear your Creole.

Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words

How does one say "so be it"? "If that means I can't go with you, then so be it."

Mwen menm, mwen t'ap di "dakò" pou tradui "so be it".

"If that means I can't go with you, then so be it."
"Si sa vle di ke m pa ka ale avè w, enben dakò."

So be it
dakò
kite sa fèt konsa
antandi
ensiswatil
Amen!

Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words

Are there other ways to say "ti fet la" (the party)? I am assuming that this is a party in general. Pa vre? Mesi.

Wi, se sa.  Ou byen di.  It's a little party or a little gathering

yon ti fèt
yon ti rasableman
yon ti selebrasyon
yon ti festen
etc....
Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words