Looks like you don't really know what you're talking about. Everything you're mentioning is a non-issue.
First of all, if you're playing against a team who's paid by Riot are you really not gonna be paranoid about it
All teams are paid by Riot in partnership (base salary players, anything on top of the minimum is provided by Orgs). Are you not aware that Riot pays each team/org currently in partnership, per season?
Second of all who makes the roster changes?
As an FA team you'd still have to abide by the same rules: aka have a coach and substitute player available (if still applicable). In this case, it would be a decision between the players and the coach (similar to how it is done in existing Orgs as well)
Third, you can't do that forever
You don't do it forever. You do it for 2 VCT seasons, since that's how Ascension works.