Sorry Han I think your pass on the 2nd hand is terrible

You have the stiff club and it's pretty likely partner will not be able to reopen when both 3C and 3D are making.
Hate to use the LAW but it looks like there is probably ~17 total trumps and I would guess 18 is more likely than 16, and we also have good diamonds and our spades are good for offense (the suit we expect partner not to have 3 of, the ace empty fifth is a very nice holding), so if there are adjustments it's upwards not downwards. It also looks like the points are distributed about evenly. It's just a classic hand type where we need to compete to 3D over 3C.
You will win if partner has extra values and will X 3C and pass 3D, but bid on over 3D, but that seems like a less likely hand type and even if he does have that hand type we could easily survive in 4D.
On top of all of this, what if it's a big fit type hand and LHO is about to bid 5C and we need to bid 5D either as a save or a make? That is not ruled out at all yet, and in that case it is very important that we bid 3D right now imo.
It seems like you overthought this one.
I did not comment on this one or the last one because I thought they were equally obvious (ok the last one is not obvious WHAT to bid, but you must drive to 6 of course).