I’ll respond to #3 above, only because I’ve shot both the underwood and BB 150 gr full wadcutters alongside the 135gr GDHP+P on several occasions in different revolvers. The recoil across all 3 loads, IMHO, is pretty darn close—which makes me just go with the GDHP. I don’t really see any advantage to the hotter 150 wadcutter loadings, unless one lives in NJ or uses an airweight J as a “black bear gun.” Neither of which I ever plan on doing.
TL/DR there isn’t anything the hot 150s do that either the GDHP+P or a serious “outdoorsman” load, eg. either boutique maker’s 158 gr +P semi wadcutter at 1250, won’t do better. JMO.