Hi and welcome among us @ELIOT_theSuper,
So first of all, minting MP4 seems to return errors by now so be cautious !
As you may have read, technologies behing minting ERC-721 or ERC-115 are quite different but you summed up the other differences accurately.
Technically, the ERC-1155 is very expensive, but if you have a global theme where you’ll post most of your NFT, it may be interesting because they will be indexed under a 'super-theme", plus, once verified, they will appear in the hoty collections on Rarible.
In my opinion, going over 20 items of the same NFT quite kills it’s uniqueness. I minted one NFT in 50 pieces so as to gift them occasionnally to buyers and sell it at a lower price. So yes I totally agree that the less is the better, but it implies producing a lot. I think ten copies is quite satisfying unless you want to do a giveaway.
Your prices seems quite high. Unless you have a strong community in the real world ready to buy your NFTs, I would advice to begin with more reasonable prices and mint more expensive pieces once verified.
Auctions are new and I don’t think it’ll suit you as only verified users are presented on the Rarible homepage. You’ll have to communicate a lot about it to get some bids, and remember that when you accept a bid, you’ll have to pay the gas fees for the transaction.
Hope it helped.
My NEW NFT here, here, here and here (NSFW). My profile is here
I always follow for follow, even on instagram where you can see my other pieces and my painting process.