I think high end overclocked 1070 Ti's will get 32-33 MH/s on ETH and ~520 H/s on Equihash, depending on the model. Not worth it considering the 1080 is about the same price and AMD RX series cards are much more cost effective for ETH.
Probably 580 sol/s or even 600 sol/s. GDDR5 is better than GDDR5x for mining, even on equihash
Very doubtful. Equihash is much more core dependant and GDDR5X memory overclocks much better than GDDR5. I can push the memory on my 1080 to +1000 MHz with no problem. My Zotac AMP! Extreme 1070 can go to +700 MHz max.