Hello vno & welcome to MR.
If you load the books direct onto the reader (registered with Sony) you should not have problems with opening them.
For the DRM thingy, check out this thread
here.
For anything regarding the reader, check out the
Sony subforum. Lots of help there.
Have you found the
download section yet? All classics out of copyright, lovingly formatted by MR readers.
Another good source for freebies & deals in the
subforum with same title.