The Leader of Bitcoin is the Bitcoin Dev Team : Blockstream
Nope. Again, there's no leader in bitcoin and by that I mean an entity that affects it in such an intensive way, that if Blockstream moves to another cryptocurrency, the bitcoin community would follow likewise. This kind of leadership exists in Ethereum for example, where Vitalik decided that the community should abandon Ethereum Classic's chain.
Bitcoin suffers
the least from any other cryptocurrency project due to its significant ideology.
You should actually study Proof of Stake, you would learn alot.
(Go search Cardano or Algorand resources for information, it will enlighten you as to the truth.)
I will, sometime in the future, as I haven't studied a lot those two and I'm in favor of not having a biased opinion towards altcoins, but I've seen enough to have my disagreements for some.