You have all good points in your posts. We have a good FAQ on the website, just check it on the main page or a t the address
https://www.psfantasy.com/hardware/ps2/online.php
If you have questions, ask us and we'll add them in the FAQ.
By the way, most of the games going to be releasd for Ps2 *should* be playable with normal dial-up connection. Of course, many of them will have limited features with narrowband connection. For example, TW: B Online is playable with narrowband, but it allows only two-players games; the ones with a broadband connection will be able to enjoy 8-players games.