[deleted]

My attempt for the first sentence

Daha karpuz kesecektik

We were about to cut more watermelon.

my attempt

Mesajı samimi buldum da yazdım, sanırım bir sorunda teşkil etmedi.

I found the message sincere, and I also wrote, I guess it did not prove to be a problem. 

and more attempted 

Neyse sana pofur pofur bir gece diliyorum dostum.

Anyway, I wish you a great puffing night my good friend.

Daha karpuz kesecektik.

We will cut more watermelon. (i guess from the letter this kind of means we will discuss more, or go into more detail)

Mesajı samimi buldum da yazdım, sanırım bi sorunda teşkil etmedi.

I found the message to be sincere and i wrote, thinking a question didnt form. there wasn´t a question.

 Neyse sana pöfür pöfür bi gece diliyorum dostum.

Never mind, i am hoping my friend, to you a night with poof!

ben uyumayacağımdan açık cam ilen gayet mutluyum.

i am not going to sleep because  i am extremely happy with the open window.

Tamam zaten eklememde çok içten bişi sorcam, ikide bir by demek temel bi içgüdü mü yoksa gerçekten bi işi var-ki bu saatte zor - yada uyumak falan mı istiyorsun?

ok, in fact, additionally, i will ask something very sincerely, in two - one to say foundation one instinct  or from reality there is one secret - whom in this hour difficult -  Do you want to sleep with the enemy you-know who?

i tried, but i have no idea what it means... i just tried because i want to test my skills.... and check how others translate. i think my translation should be ignored...

 Henry your literal translation is correct, i just like to explain what the person meant by saying that weird sentence;

" Daha karpuz kesecektik  is a kind of  joke that we say to a person [close friend] who leaves early.

Say ,we have our friend as a guest, he wanted to leave but we  want him to stay longer. So we say this joke to that person. [ we havent eaten the water melon yet, we were going to cut it and have it together, why are u leaving early ? ]

Henry, I want to make a tiny bit correction if you dont mind.

The conjunction "da" here works as " because".

In other words it is like " Mesajı samimi bulduğum için yazdım "

I wrote because I found the message sincere.

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sorun teşkil etmek = to be counted as a problem.,to be seen as a problem.

I guess, it [my writing to you] wasnt counted as a problem by [you].

in other words;

And I guess it[my writing to you] wasnt a problem for you.

Thanks Tunci, I guessed it was a Turkish expression (idiom) that had another meaning.

 Rica ederim Henry. Yes, it is sort of Turkish joke [although I find that joke silly and out of fashion ] 

Thanks again, I often have problems translating the separated da/de