Hi Maerose, you can charge your 505 with the PSP cable but, it takes about four hours to completely charge it and you can't read books on your reader during that period. For about $20 you can get a wall charger that'll charge up your reader in half that time and you can read while it is charging.
You can download books in advance. And you can use .lrf, the Sony format or ePub which is the emerging industry standard.
Also, you can borrow ebooks from some libraries. They're in ePub and you get to keep them for 21 days. Check the Wiki here
https://wiki.mobileread.com/wiki/EBook_Lending_Libraries