Welcome to MobileRead, Starfish!
The 505 can handle up to a 2 GB SD card and an 8 GB memory stick (both at the same time, if you like). The difference in manufacturers mostly shows up in how much drain they put on the battery.
As for your collections, if you move them onto the Reader or memory card by dragging the
collection over, then the books will show up in whatever order you have them in in the collection.
You can change the order of books in a collection by dragging them around within it. I believe the initial order is defined by the order the books are placed in the collection, so if you add them to the collection from the main listing by starting at the top and working down, they'll be in alpha order when you're done. Aside from that, I think you're left with hand sorting them within the collection.
