Hearteater got most of these.
2) I can't be sure but gifting isn't the idea. It's if you hit 999,999 in a particular item (let's say metal) and your partner has 500,000, your overflow will go to his banks. If he's at 999k too it'll just disappear. If that's not happening post a bug up in Mantis for Arcen to take a poke at. They'll probably need a save game.
3) I usually leave a bit of basic turrets or HBC near my command centers instead of the Lightnings because they're cheaper to upgrade for more of them, but same effect. Eyebots require Tachyon turrets, and by preference counter-missile turrets (2 for 1, they shut down Missile Frigs, too) and short range non-missile non-snipe defense units. Pick your flavor.
4) That's my fault. I K-Raided out about 50,000 K in a game I AAR'd and kind of got Keith's attention with that. Personally ARS Ship Choice is more important to me, but I'm used to running at lower numbers of research. There's been some mods so each of you can choose differently if you like on an ARS hack. Just science II it first and decide if you need to. K-Raiding's original intent was to get you out of a hole if you dug it for no AIP gain, and that's being more enforced now. I've found that usually I can hack 2 ARS and get in a K-Raid or two still at higher levels if I'm very selective regarding the target. You shouldn't be completely hosed up.
5) Usually, yes. I call it nerf/neuter though so I can keep track in my head when I do which, but that's a personal preference. I do kill off WHGPs on occassion but that's mostly for my high-traffic areas so guardians and small ships don't end up harassing smaller reinforcement flights to the fleet on the highways. WHGPs will not affect max population for a system, it's more a matter of them being able to be placed in the most inconvenient locations... on wormholes.