Great question. Bitmain the chines ASIC manufacture and mining pool operator are the main party pushing for this alt-coin.
BITMAIN do not support BCH. Their proposal was only for if UASF succeeds - it has, but only due to BIP 91. While they could be doing anything in the future, they're still directing their hashrate for the New York agreement for now.
with other segwit proposals
BCH does not involve SegWit. SegWit is potentially being activated on the current chain, but not on BCH. They are opposed to SegWit.
Why big hype on BCC/BCH and how they will survive 51% attack ?
Good point. I would say that after the split, some mining pools will dedicate portions of their hashrate to BCH depending on the price, and shitty cloud miners like Genesis Mining will most likely be offering BCH contracts. If the hashrate is too low relative to the price, it's likely that people will reuse their old SHA-256 ASICs that are no longer profitable on BTC, which would push up the hashrate somewhat.
If BITMAIN were to ever change their stance and begin supporting BCH as well as possible, they may be able to do 51% attacks, but considering that it would make all mining on that chain unprofitable for them and the people mining at their pools, I consider it unlikely.