1. 8
2. 1999
3. Pumpkin Studios
4. PSX + Windows, Windows + Mac + Linux
5. 1.10 is GPLv2 with a linking exception since 2004. 2.0 and higher is standard GPLv2 for most of it, but uses CC licenses for some of its content
6. Depends on what you mean by "class". The in-game definition of "class", there's only one - all forts are kinetic. If you mean types, there are two - two all-rounder forts and two anti-tank forts. If you mean techlevels, there are two T2 forts and two T3 forts.
7. ~450... or maybe that's prerequisites. ~200 techs, then?
8. Display minimap, allow design, research MG Tower (soon to change)
9. Nexus Link Turret, Auto-Repair
10. Two and a half. First one, last one, and half of Alpha 3.
11. Including unlimited, unlimited.

Excluding unlimited, I think there's a two-hour one in cam2.
12. If by "strongest" you mean "most powerful", PC, by far.

If you mean "most HP", that's TAC.
13. Depends on what you mean by "weapon" and "superweapon".

You're probably thinking of EMP Mortar, but all scavenger weapons and cyborg weapons can't be designed, either.

And does the NPM count as a superweapon?
14. Again, are we talking damage-wise? If so, AA usually has a DPS advantage, so it's probably Whirlwind. If not, Gauss Cannon has the most HP for a weapon. Unless command turrets count, in which case CT4 wins hands down.
15. Percentage-wise, mini-rockets and rockets are even. Damage-wise, TK has highest damage of the rockets and so increases the most. Missiles are T3 and thus have very few upgrades.
16. Angel and Archie. Seraph may also count, depending on how you define "artillery".
17. I assume you're talking about Vindicator here, but it doesn't have "twin" in its name.
18. Minipod
19. cyfac
20. powmod, derrick
21. lassat, both stats-wise and in practice. Excluding that, Archie is next.
22. AA missiles.
23. Mass Driver
24. Cannon
25. borg legs has highest maxspeed, though, in practice, hovers are usually faster 'cause they can be paired with better engines
A lot of these questions are made un-fun by anti-air, so here are some answers that exclude AA:
14. At DPS/A0, TAG wins. At standard armor for the techlevel you get the weapon, Scourge wins.
22. HL