I've never broken a torx bit on taking a zetec head off - even really old rusty munters. Are you using the right size and a suitable breaker bar?

Pistons: assuming you're keeping the standard rods, then they should measure the pin of the piston and ream the rod to a suitable interference fit, and then fit them for you.

You can use the earlier water pump with a suitable hole in the block, or go electric.

Sure, using a remote take-off for the oil filter would move that obstacle away, but I doubt it'd be a problem as it's in a much better location on a black top (eg, like how a cvh has it)..