1) High population planets aren't worthwhile not because they don't generate cash or influence, but because the morale required is prohibitive.
TA has slightly more income from tourism (it was down and then up in the betas, my guess is 15-25% more at this point, but I haven't run the numbers and to be honest I don't think anyone even has a tourism formula), but that's about it.
2) Covered in 1: No. Torians have a 50% morale building now, which helps, but with the native morale cap (100 after depreciation by population) that DA introduced, it's just not enough. Not to mention how hard it is to get enough native morale to begin with.
3) Not really. The attack/defense/speed boosting modules change the attack priority formula, applying a modifier to it, making the ship more likely to be attacked if it has a single weapon on it (so much so that you can make a tank now), but it's still attack / defense + hp.
How weapons work against armor hasn't changed.
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I'm adding things as I remember them. 
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One thing that may interest you, since you want the crunchy number goodness, is that in TA focus still takes 25% of the first production (say social --> research) but only gives 20% to the second production (so 100 social production focused on research becomes 75 social production, 20 research production, before any bonuses are applied). This is a direct modifier and is not an extra modifier of 80%, so there shouldn't ever be any truncation. This has the side effect of making focus, and hence all-labs or all-factories, somewhat less effective.
Social <--> military is unchanged at 50% shared, it's only when the production types are generated from different buildings that the deficiency modifier is applied.
Also, the tech capital has changed in TA, such that it adds to the base research at the last step (after bonuses have applied to base, say 150 x 1.2 for 180, it adds the base, in this case 150, for a total of 330), rather than being a straight 2x multiplier. So the higher research bonus that you have, the less of a relative improvement you will see with the tech capital.
Impulse Drive Mark II & III have been changed from their DL tech values to equal to DA's Impulse Drive I, at 400tp (from 200tp/300tp respectively).
Nano Recorders, available from Sensors III, has been reduced in cost from 540 production to 100 production.
All weapons trees cost less in TA than in DA; all of them are under 25k if memory serves, whereas in DA we had 49k for beams, 67k for guns, and 76k for missiles (give or take).
There is an additional 50% modifier applied to all of the TA weapons and defense techs (didn't get around to checking hulls or invasion techs yet) beyond their cost that is hidden and only shows up in the game, so Galactopedia doesn't show it, but even with this they're still vastly cheaper than in DA. Also, since this applies to defense techs as well, the gap between weapons and defenses widens even more in the favor of weapons.
