The only optional rule that any of you needs to be concerned about right now is your first one-- the customizable Backgrounds. And as has been said... the new DMG that comes out in a couple weeks will have the "official" instructions for how to do them-- although everyone and their mother has easily figured out what they are going to look like. So asking the DM if you could possibly amend an existing Background or create a new one is not a big ask. These bits and bobs are so interchangeable that I don't see how any DM would really care if one of you were to say "I'm making a Cleric and want to take the Acolyte Background. But as I don't think I'll need the extra spells from the Magic Initiate Origin feat, might it be all right if I just swap it for the Tough feat for the extra hit points?" That's so much a nothing-burger ask that I don't see how any new DMs would really be worried about it.
As far as the other two points... the second point you won't need to worry about until you all reach 4th level, which might be several months or more down the road. At that point the DM might be much more comfortable with what they are doing and thus more amenable to hearing pitches for adding a +1 ASI to an Origin feat selection at that time, rather than now (when it doesn't even matter). And maybe at that point down the road none of you will actually WANT to take a second Origin feat, so the question of the +1 won't even be asked-- so why bring it up now and possibly put the new DM back on their heels? And for the third point... you have several years before any of you even sniff at the possibility of Epic Boons, so none of you need worry about that at all right now. No reason to freak out the DM for an ask that most likely will never occur anyway.
