By pin do you mean the "pad" the end of the arm rests against and pivots on ?, if so no longer available from ford, I fabricated one out of delrin for my own T5, when I did my own hydraulic conversion which is well worth doing whilst it's apart.
As for the flywheel, I'm confused about with "long bolts welded to it", if you as I assume are referring to the normal through bolts in the centre I can't see how you're going to attach the 9 bolts to the crank.
As for being balanced as one with the crank don't worry, although ideal so long as it is balanced on it's own that is fine, not all engines are apart, and millions of flywheels are balanced/re-balanced without them being as one unit with the rest of the engine with no problem.
The flywheel does have the ability to affect the idle quality, this is mostly dependant on how well the mapping is done how light the flywheel is, but most importantly what cams you are using ?, if using std cams don't even worry about it, there was a thread on here about lightened flywheels asking for views/experience well worth a read I've used them for the best part of 30 years, and didn't regret a single time doing it.
tabetha