Okay, with regards to powers and their transition. Here's what we'll do.
Any given power will have to pass three checks at its own level value to pass the world barrier unhindered. "Pass" in this case means scoring a "Success" or higher. So I roll the check as if you were using the power, three times, and if you succeed all three it remains the same. If only two succeed, the power's die value is halved, rounded down. If only one succeeds, the value is reset to 1, and the power is, for all intents and purposes, lost - but it could be regained with proper effort. If all fail, the power is lost forever.
With this system, the chance to lose a highly developed ability is fairly slim. The chance of losing any ability at all (as long as it's up to "reasonably successful" levels) permanently is also rather low, but there's a high chance of pushing underdeveloped abilities into outright uselessness.
For items, it'll be a bit different. It'll be the same system, with items receiving die values from 4 to 8 depending on how tied to their universe they are, but there will be no gradation. The item will keep its powers if it fails no more than one check.
There, I think this is a fair enough system to use.
As for the other variants - the scenarios one wasn't really an option (hehe), since some of the worlds I selected already make use of that mechanic, and would be positively dull to play in otherwise. I just wanted to see if anyone had opinions to share on the concept. And I'll probably forego the initial race selection, unless someone from the starting 5 players wants to change - no use scrapping perfectly good characters.
And yeah, still working on that update. God damn this is hard. How do professional writers do this kind of thing?