As long as you are OK with voiding your warranty with the manufacturer, do as you like. All warranties are provided with the proviso that temperature and humdidty control must be kept in a fairly narrow range. Purchase of an engineered product would have suited your lifestyle more than solid wood. That is something you should have accounted for in your research phase. If you are OK with some rather large gapping occuring 6 months out of the year, then go ahead with the install as you've planned to without AC. If you prefer smaller gaps 6 months out of the year, then at least run the AC for a couple of weeks before the install to help pull out all of the construction moisture (which is considerable!) and then turn it off for a couple of days and then install. Any of these scenarios will void the warranty and leave you with no recourse even if a different manufacturer's defect were to manifest itself. You take whatever path you wish, but with full knowledge of the consequences.

We used masonite sheets over the rosin paper which really helped the tromping/scratching factor. And honestly, I'd rather take my chances with the cabinet installers (who are generally carpenters) hurting the floor, rather than the flooring installers (who are generally not carpenters) hurting the cabinets. :-) It's also a lot more work to cut around cabinetry that's already installed, so chances are the savings in square flooring footage will get totally eaten up with the extra labor time, anyways. And unless they are really skilled, you will wind up needing shoe molding to hide the small gaps between floorboards and cabs/toekicks.

The answer could be "Yes". It could be "No" or it could be "maybe...it depends". The trick with this is that new hardwood does not like sitting over top of OLD finishes...like polyurethane. And new hardwood needs FLAT. So the chances are VERY high that you need to SAND DOWN your old hardwoods (to remove the finish AND to flatten any obvious areas of concern). That should cost you $2/sf. Now the fun part...getting patch down where it is needed. It is possible but old hardwoods don't normally like to have concrete patch put down on them. They can. But they aren't fond of it. The cement patch often cracks and disintegrates as those old floors move. You will still need patch = $1/sf (on the LOW end). The other fun thing is: you probably have to install the floors perpendicular to the old floors....which will be AGAINST the installation instructions/warranty (most hardwoods must be installed perpendicular to the joists...which would be your OLD hardwoods...but the NEW one's would be perpendicular to THOSE = parallel to your joists = against all "Best Practices"). The way around this = DIAGONAL (lay it at a 45deg. angle). This should increase your WASTE into the 15% range = 15% more expensive than anticipated. So if you add up all the "trouble" you will go to, you will be paying about the same or MORE to do this. Of course you could throw down some plywood over top the old hardwood = go ahead as a normal install. But that puts you too high---so your ONE option to do this "cheaply" is not on your list. Go ahead and remove those old hardwoods (I'm assuming they are so OLD that they cannot be sanded and refinished). Lay new plywood and then install the new hardwood. The cost to do this properly should add $2-$3/sf (labour and plywood included). If you do this the "cheater" way, it should cost you $2-$6/sf (that includes the diagonal install with extra waste) and lose you your warranty. After all that money for the hardwood and install, that would be a sad state of affairs.

I like to see floors going long upon room entry. I feel it gives more spacious look. So I would run then long in your case.