no EWR-BOM. Not much to add here.

Buy-up to PE with cash can be reasonable. Only way to know is to try it.

FRA-BOM on LH you can upgrade on lufthansa.com. Try to get an LH coded flight FRA-BOM. You cannot upgrade from Y to F on LH ... There is no way to waitlist that either. If your booking class is eligible you can try for an UG to C on LH using +Ps. India flights are not easy upgrades