How will the 2mb hard fork be implemented? With regards to SegWit2x/BIP 91. If SegWit is successfully implemented around Aug 1 what is required from the miners in November to implement the 2mb hard fork successfully? Is it also a minimum 80% signalling via blocks on predetermined dates?
August 1st has nothing to do with BIP 91, nor will segwit become active on August 1st due to either of BIP 148 or BIP 91. The current projected date for segwit to become active (assuming that BIP 91 is enforced) is August 24th.

The segwit2x hard fork to 8 MB block weight is currently implemented as occurring 12960 blocks following the activation of segwit. For this to happen successfully, all nodes and miners must upgrade to software that implements segwit2x. The activation will be by flag block; there is no miner signaling.