Summoning is pretty much an all or nothing affair for the pets, but it's situationally good to have two into the school for Charm in a split group. The Incarnate really shines though in either an all elemental damage group, or a split group.
It mostly sucks in an all physical group other than having kind of a distraction, an extra Battle Stomp and the ability for the caster to deal damage at a range they normally wouldn't be able to on the first turn. It just can't keep up with the physical damage characters can do thanks to the crazy item scaling though. At best you end up with a beefy distraction that can supplement the "okay" damage of the caster until the caster also has 10 in Warfare, which is late game. There's pretty much no reason to infuse it with an element in this kind of group either.
It's an absolute monster though in split or an all elemental group however. For whatever reason, the Incarnate hits way harder with the same spells that a player can use even at the same rank in that element. They can only cast two spells, but they hit like a truck and are also cheaper in that they are "free" aside from the single source point you spent for the infusion. The same spells for the player would cost 2-3 source points and do less damage (WTF?).
Healing is overrated and you will almost never have any need for anything beyond the basic Restoration spell. The Huntsman's First Aid is useful mostly for the caster, but it removes some rather annoying debuffs on top of the healing it does too. Most of the time potions are more than enough and you'll barely need them either. Keeping your armors up is more important. Two-Handed isn't that good until level 10+ and it doesn't get great until close to end of the game. The best physical damage dealers are Rangers and Rogues.
Haste is a questionable use of AP to cast on yourself unless you're using it to remove Cripple and Slow. It essentially costs 1 AP to move you an extra 2m per AP spent (so up to 6m on a typical first turn) since the AP you gain from it makes it a zero sum total. It's not terrible for 1 AP, but it stalls your first turn. Polymorph is a great tree, but it's only situationally useful to go beyond two points for a long while, and even then it might not even be worth going beyond the first rank until late game. Flight is a good skill, but its use compared to the other movement options is dubious. It costs two AP for the first time you move with it and then one after on the next two turns. Phoenix Dive, Cloak and Dagger and Tactical Retreat (which you most likely wouldn't have) all cost 1 AP and move you the same distance. It's rare that you'll need to actually move that many times in most encounters anyway, because even if you do end up using it a third time, chances are it was to move to the complete opposite end of the screen from where you were and even then you still would not have reached the last enemy or two--which will most likely already be picked off by your other characters anyway.
As far as keeping armor up, Fortify is better than both Uncanny Evasion and Heart of Steel (it also removes burning and prevents teleportation), although if you don't want to spread your points out too much, even Bone Cage is better than the other two options, especially since Necromancy has a handful of really useful buffs, debuffs and situational healing that work well with melee compared to both Aero and Geo.