Hello!

Here's a translation of the passage, part by part (Are you sure, though, that this is not personal/confidential correspondence?)

Prodade li cherwenata formula..Hondarata?:
Did you sell the red formula, the 'Honda'?

razkazwai,momche.....pochti wseki den si proweriawam poshtata za pismo ot
teb:
Tell me (what happened), buddy... I check my mail every day to see if I have a message from you,


nadiawam se i chakam,no.....tia wse e prazna...:
hoping and waiting.... but it (my mailbox) is always empty...


mnogo iskam da mi pishe
edin strahoten priatel,kazwa se Emil Tchilian,triabwa da go
poznawash...:
I want very much to "be written to" (meaning receive a letter from) by a great friend of mine, his name is Emil Tchilian, you may know him...

Toi e turbo hiper pech .....i..nai-dobriat mi priatel...
He is a "turbo" "hyper" great buddy - and my best friend...

Here's a translation of the passage, part by part. Are you sure, though, that this is not personal/confidential correspondence? It seems strange to me that you should want to know what the letter means. But as it seems to be a pretty innocent text, I'm translating it for you:

Prodade li cherwenata formula..Hondarata?:
Did you sell the red formula, the 'Honda'?

razkazwai,momche.....pochti wseki den si proweriawam poshtata za pismo ot
teb:
Tell me about it, buddy... I check my mailbox every day to see if I have mail,


nadiawam se i chakam,no.....tia wse e prazna...:

hoping and waiting.... but it is always empty...


mnogo iskam da mi pishe
edin strahoten priatel,kazwa se Emil Tchilian,triabwa da go
poznawash...:
I want very much to "be written to" (meaning receive a letter from) by a great friend of mine, his name is Emil Tchilian, you may know him...

Toi e turbo hiper pech .....i..nai-dobriat mi priatel...
He is a "turbo" "hyper" great buddy - and my best friend...

That's too much personal. Depends what you want to say.
Friend is the most general one. No special sentiments. No special attitude.
Nothing special. That's it.
If you want to sound seious use friend.