If you can't drill and use a easy-out to get the threads out, you may have to have a machine shop remove it.
Any time you replace the clutch, you should resurface the FW.
Yes, the TSK3 kit is one thing you should have.
I wouldn't bother powder coating the those.
contact m sprank or Mike at AZPinstalls.com and see what he recommends for a clutch set up.
226,000miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. CHECK your oil, these cars use it.
Engine Build - Click Here