The formula for generating what levels give new talents is:

f(x) = (3x^2 + x + 1)/(x - 1)^2

Speedcreeper was removed?

Does guerrilla work if character is invisible as well or do they have to be sneaking in sneak mode?

Glass cannon on all 4 characters (bad idea for lone wolf, due to much lower relative AP gain). Surprisingly powerful. It is very rare that the AI actually CCs one of ur characters. Spreading out is quite important though, as certain aoe knockdown skills can ruin ur day (such as tremor grenade, or the warrior knockdowns). Eventually ull have some spells/means of removing CC from ur party. Few times i ran into fights were the "boss" had some aura like vacuum. Just gotta chug one of those strong will potions and continue to stomp everything into the dirt. The advocate fight was particularly amusing. Boss cast madness on my entire party, and it was entertaining to have no control for 2 full turns. With heavy con summoner build everyone still survived, surprisingly. I see little reason not to take glass cannon, as with experience, u can prevent CC from taking place entirely (CC them b4 they CC u with the extra AP), or just cure the CC on ur next character (CC curing is nice to have around regardless, so not losing out on much tbh).

Those saying Lone wolf is bad/a trap is just wrong. The only issues with early lone wolf is you'll have 2 allies rather than 4 but that is also a pro. With only 2 allies you stack best equips on them and don't spend money/spell books on twice the amount of people. By the time you're really attacked the Fort Joy guards you should be much stronger than a 4 party. It's important to have focus either on phys/magic damage depending on the foe. Knights/Rogues with some spells or Mages with Summon/Witchcraft do that nicely. I did a Knight/Rogue lone wolf and cleared it on Tactician with a fair amount of ease - Living armor doesn't get enough praise here either. It's amazing with the passive heals from witchcraft, soul bond, etc. there's just a dozen ways to keep magic armor on which is hugely important.

Will the new gift bag talents be added?

Decided a newer write-up of best general talents was needed from someone that plays Tactician/Honor Mode.

If you're not using the Gift Bag Pet Pal, give it to at least one character by level 3 for extra quests/exp.

After deciding on Lone Wolf/Glass Cannon or not (I prefer Lone Wolf myself), the most important talents are AP efficiency related:
Elemental Affinity for mages, Opportunist (AKA 0 AP attacks) for melee, and Gladiator (from Gift Bag) for melee w/shield.
Executioner works for everyone that does damage, give it to your primary finisher early, and add it to others when you've eliminated the better options. (It also triggers on Opportunist attacks, Reactive Shot, etc. when you get a kill and applies the AP to the start of your next turn!)
For Fire/Earth mages, Torturer in the early game is also the equivalent of extra attacks, plus it makes Worm Tremor an unblockable CC and Spontaneous Combustion more powerful. It also means extra healing when you poison undead.
And Ambidextrous for those that want to take the time to craft and abuse scrolls.
You'll want at least 2 of the above by level 8.
By level 8, you'll also want Living Armor for tanks, Parry Master for dual wielders, and Savage Sortilage for mages.

By level 13, you are probably pumping crit, Hot Head is great for everyone as it's easy to maintain max vitality.

Your build's talents should be mostly done by level 13. Late game, you may want to throw Living Armor on non-tanks as well. You should also be able to afford giving mages Executioner around this time. And Sadist (Gift Bag) can top off your melee types.

Other Notes:
Given the amount of fire surfaces and damage you'll see in game, Demon is a reasonable defensive choice as well.
Fire-Star Diner has some (ab)uses as well if you have the stomach for consumables, pun intended.
Mnemonic is an okay choice for non-Lone Wolves when you can't remember what else to go for (yay, more puns).
All other talents are either class/build specific or trash:
Low vitality/revival talents are essentially saying you are planning to fail. The Idol of Rebirth is far better insurance.
Unlike many, I'd argue against The Pawn. Most ground/cloud effects make movement skills the better option. Being an executioner is a far better choice than being a pawn. (Hah, executed one last pun for the road!)
Far Out Man isn't as useful as being on higher ground. So again, it's better to give your ranger/mages movement skills to take the high ground and make better use of the talent point.

Those wishing for an extra talent on one of their chatacters can do so in the Past Mistakes quest. initially free Karon from Arx sewers, then kill him when he reappears after the Trial of Blood. Talking to his spirit and passing a persuasion check will grant that character (only) an additional talent point.
Opportunities to use the extra talent may be limited due to being very close to the end of the game however better having than not!

Does anyone know if Soulcatcher from the gift bag scales with Summoning?

Is there a way to reset my talents?