Qilin, or Kirin, are replacing Angels this set as the big white flying creature.

I'm not sure what you mean with "perforated cards" - are these like something you poke holes at? That's would be... unpractical?

Couldn't you just like exile these and use them as reminders that way? Also, in a case like this, I would have them rather gain all abilities than "any number of". Why would you not want to give all of these abilities anyway?

I'm building a (really bad looking) mockup right now of what I mean by perforated cards, but they'd be similar to the Embalm/Exert/Brick Counter cards used in Amonkhet here.

In regards to exiling, it is something I've considered, but I'd rather not do it at the moment. I'm not a fan of exiling the card as a reminder for every mechanic that requires memory when being used from the graveyard; I think it's working too much with the boundaries within the game while not really exploring any solutions that can be found for memory issues outside of the game. Checklist cards for Double-Faced cards is a similar, questionably elegant solution for logistical issues that a mechanic presents. It's entirely possible that Bequeath is a terrible mechanic without the exile clause and will need to be adjusted later, but I'd rather start off testing without exiling and using something new-ish (using perforated punch-out cards like in Amonkhet) and adding it later, than starting off playing it safe and never really trying out any alternative solutions.

In regards to the "any number of", it's the same reason why you can give the abilities to your opponent's creatures - it's to open up space for negative abilities later on, like the one illustrated in Servant of Guiwang, where you can choose to give an opponent's creature "lose 2 life every turn" or give one of your own creatures flying (or both to one or the other for some reason). I originally had it as "When this dies, you may have target creature gain all {+} abilities on this creature.", but I figure the more flexible the mechanic is, the more I can tweak it and iterate on it later.