This is our post address, and on this address we are waiting for the original of the contract:
125167
Russia
Moscow
Aviacionni pereulok, h.7
For “

In Russian: 125167, Россия, Москва, Авиационный переулок, д.7, для ЗАО

We are ready to sign agreement as soon as possible and we are ready to effect the payment when you give us the account.
Thank you very much for your understanding, we are happy to deal with you.

...when U provide us with the account details

хотелось бы конечно вараинт на русском

1) at this address
2) provide us with your bank(ing) details

Можно написать так:

Please revert one (2 or 3) copies of the original fully executed contract at our address as follows.

Мы бы хотели подписать догвор как можно быстрее и мы готовы произвести платеж, как только вы укажите счет.
Спасибо большое за ваше понимание, мы очень рады с вами работать.
А я "авиационный" правильно транслиттелировала?

We would like to sign(execute) the agreement/contract at the ealierst possible date and we will make payment as soon U provide us with the account details.

aviatsionnyi - имхо

We would like to execute the contract as soon as possible. We are ready to make the payment upon receipt of your bank details.

Thank you very much for your understanding. It is our pleasure doing business with you.

Aviazionny pereulok

Here is our address to which you should send the original of the contract:
125167
Russia,
Moscow,
Aviacionni pereulok, bldg. 7
ZAO.....

We are ready to sign an agreement as soon as possible and are ready to make payment as soon as you provide us with the account number.

Thank you for your time and consideration. It is a pleasure to be working with you.

you could also say in this letter:
"please send the original of the contract to the following address"

--- if it will not be an inconvenience for you, please indicate in which way you normally exchange documents with your Russian partners."