I havn't checked this in a while, so sorry if this info comes a little late...
Erik, if you want to edit text on a PC and then put it in an emulator of some sort, you have to use an ASCII to ATASCII converter. Straight up ASCII values like lowercase and uppercase chars, numbers, and symbols are almost all the same, but I'm sure you're aware of the Atari's "inverse video" characters. The only major thing aside from inverse video chars is the ATASCII EOL (End Of Line/carriage return) character. It has a value of 155, and on an IBM, that get's you some obscure symbol that I don't recall.
Ravuya: I have a load of 1050/DOS 2.5 manuals. If you need me to, I can scan one for you, or even give you one if you'll pay the postage.
Also, Ravuya, what version of DOS are you running?
As for saving from BASIC, try typing your save command as SAVE"D1:FOOBAR.BAS". If you have an actual Atari DOS, "D:" defaults to D1: so you can ditch the number 1. If it's some other DOS, you may have to specify.
If you are just getting into the new Atari revolution, I strongly recommend that you check out
www.atarimax.com and get APE and the cable for it. It is well worth the money.
Good luck with your new toy!