Some questions about the order.

Prosiłbym by ktoś sprawdził mi te kilka zdań i w razie czego skorygował błędy ;)

Hi. My name is xxx and I'm from Poland. I would like to buy some of your products and because of that I have also some questions. First of all I would like to know how can I pay for that? I would also want to know whether your company will deliver my order to my door step and how long I will have to wait for it?

Yours faithfully,
xxx

Hi. My name is xxx and I'm from Poland. I would like to buy some of your products, consequently I have some questions. Could you please inform me what the terms of payment are? I would also want to know whether your company will deliver door-to-door and how long I will have to wait for the delivered items.

Przepraszam, ale czy nie jest to blad? Czy koncowka zdania nie powinna brzmiec, np:
for the delivery?;
for the items to be delivered?

masz rację for the delivery

", and because of that" - to można zostawić, ale jak kto woli :-)

Well done to you!