Yes, the ph being out of range can lock-out nutrients, causing the nutrients to be stolen from the fans. (no nutrients, the leaves yellow) Really low ph causes the leaf to curl, looking like a claw.
No, the yellowing of the plant will not alter the ph.
Yes, overwatering can cause the same type of yellowing. If it continues, you'll start to see greyish brown to brown splotches growing on the leaves as those spots die.

My wellwater comes out at 7.9 to 8.0 ph. I use phDown (phosphoric acid) at 1/4 tsp per gallon (4 litres) and it brings me down to 6.7ish. Cannabis in peat-based mediums (if buffered) should have an ingoing ph of 6.3 to 6.8 ph. Go outside that range and lockout starts.