I’m about to install my first HW flooring installation and have some last minute questions. Here are some details first: 1) New flooring is prefinished 1/2″ engineered flooring (Thomasville brand) with a Jatoba veneer 2) Room is 10×12 with joists at 16″ on center (some are closer due to duct work in basement). It’s a dining room. 3) Original subfloor looks like it’s 1/2″ plywood. It’s definitely not 3/4″. Very bouncy and squeaky…nailed down. Questions: 1) I will put down a second layer of 3/4″ plywood. Will overlap old seams by about 6″. Is this sufficient? 2) Current subfloor is not the tongue and groove plywood that I see used alot on (OK, I’ll say it) the home tv shows. Should I go for the tongue and groove plywood or is that not necessary? 3) Since I will have 2 layers of plywood down, should I still run the new flooring perpendicular to the joists? I would prefer to run it parallel so it matches my living room (joists under living room run differently from the dining room). Looks are secondary to sturdiness here. 4) My house is very dry this time of year. I do have some cracks in trim around the house due to the wood shrinking. I know with solid HW, you have to be careful with swelling causing buckling in the summer if the wood is nailed too tight. Is that a concern with engineered HW (wood will acclimate to the house for a week per the manufacturer’s instructions – however, they don’t address possible humidity changes with the seasons.) Thanks all in advance.