How much of this load bearing wall can I remove?
Substantial changes to a load-bearing wall really an engineer's review. The consequences of getting it wrong are unacceptable.

When it came time to take out a loadbearing wall in my place, I hired a contractor, who brought in an engineer to calculate exactly what size parallam beam would be needed to span the gap and how to provide the necessary support below the remaining stubs of wall  which were now taking the additional load.