I think your questions call for professional expertise. Even if you do the actual labor yourself, some paid advice or some advice from an extension agent or similar official might be economical in the long run. But I'll throw in my two cents anyway.
Don't know about the thinning. If the trees are big, it will be hard to cut trees down without them hitting and damaging the other trees. A person with woodlot management experience might be called for. I wonder if this was an intentionally planted woodlot in the past since you have so many trees of one species growing close together? If you have some time to do things you might try one or more of the many products you can use to degrade the stumps, some of them quicken the rot and some of them act like a slow fire. It is probably best to herbicide the stumps after you cut. Some deep root pruning around the trees that you want to keep near the edge of the construction area might help in the long run since the construction area will not be hospitable to roots and it could help disentangle roots of the trees you will keep from the ones you will cut. Otherwise, it sounds like the stumps have to come out with heavy equipment. If roots are intermingled it will be near impossible to avoid damaging roots.
The lack of brush may be due to your having a thick canopy blocking out sunlight or, as often happens around here, hungry deer might even be eating them (deer around here even walk into neighborhoods where they previously had not been seen for several decades or more and eat ornamental shrubs in people's yards, I've even seen them by the highway in the Bronx!). Do you get any saplings or do you have only mature trees?
FYI, we have lost a number of mature oaks during the last two years so I am always hesitant to cut down an oak. Hopefully, this is just luck of the draw and not a sign of an oak disease hitting the east coast.
Best of luck and congratulations on your new lot.

There is a mixture of tree sizes, from a couple inches up to maybe 18" caliper, and some of the smaller trees are different species, such as gum and maples. There are some large but very old furrows, so I think it was logged many years ago and then left. The canopy obscures the sky almost completely. I will definitely try to find an experienced person to look it over. Where the driveway will go is mostly sickly looking pines, so they can go. I think the rest of it is too closely growing for an optimum mature forest. I realize nature will eventually do this; I'd just like to help it along. From what I've seen there, they cut the trees for timber, and then rip out the stumps w/ BIG equipment. Then they push it in a pile and burn it. Doesn't seem like a very friendly way to greet the new 'neighbors'. I think I'm going to have to at least supervise if I want to minimize the damage.

If it were my lot, I would have a professional such as a certified arborist look at the situation and make suggestions about what needed to be done. One consideration is having trees within striking distance of your new home in the event of storms or disease bringing them down. Any tree close enough to fall on your house needs to be evaluated in order to protect your home. It's no guarantee none will ever damage the house, but it's better than having some simple summer thunderstorm come up and destroy what you're trying to establish. Hurricanes are another story entirely!

Clearing the trees and building a home changes the soil structure, underground water supply, and sun exposure of the area to the point that some trees may die simply because of the added stress. I've seen that happen all to often here. There are techniques to help prevent some of this and they should be considered.

The stumps can be ground out with the proper equipment. It will probably be more expensive than the usual technique but it's something to think about since it is less damaging to the surrounding roots. The problem with this method is the fact that a large portion of the stump remains underground (grinders usually don't go deep enough to get it all) and that will rot over the years. If they are in the "footprint" of the house, it won't work since you can't have that decay resulting in a weakening of the foundation. But in other areas it is an option to consider.

Good luck. It sounds like you have a nice property and are well on the way to protecting your assests.