A question about Online For PS2

Hey guys. Im thinking of getting an online adaptor to spice up my game collections. What I want to know is:

a) Are there still many gamers online? (e.g for games like Ratchet and Clank UYA)

b) Is there any kind of fee?

c) Can you take a modem from the PC and hook it to your Online Adaptor?

I know the OA is hard to find, so Im either going to search in a few more stores, and if I cant find it, Ebay!

Thanks for your help

P.S I know the questions sound silly, but I need to be 100% sure.

1. I don't know.

2. No.

3. You have to use a modem in order to hook it up.