Eric,
Your "a" point sounds reasonable. Besides, I don't think this is a project that warrants blasting. If you were REALLY concerned for bearing stability and horizontal shear, you could drill and grout epoxy coated #4 rebar dowels into the bedrock...jeesh, that would be overkill and I highly doubt it would be needed. Most of the piers that I have seen on this forum set the vert timbers right into the concrete and it sounds like you plan the same. I cannot argue with that method...it's as old as the hills. For me, I still see my near future project with a concrete pier supporting a SS post anchor and going up from there.
WRG to the 4 x 4's. Upgrade to 6 x 6. 4 x 4's will twist and crack. Yes, 6 x 6 will also, but the additional mass will reward with additional integrity and stability. If you are planting these things permanently in concrete, git it rite the first time. Don't pull up short.
For my/our benefit, and most importantly, take pix and show us your progress. I'm relyin' on you guys to keep me pumped.
edit/footnote: is there any fear of compromising your pond "seal" by drilling down to a rock layer???
