I recommend you to use companions, to add physical damage. Later, magic dmg will be weak! I'll base my replies on this.
I think Crafting and Blacksmithing is very good, because it can create very powerful gears like 2h axes that do about twice the damage of weapons you can loot or buy. You also don't have to depend your luck of finding good stuff. I max these on my active characters, because it's way more convenient, they don't require much investiment (talent, trait and gear bonuses) and there really are more than enough points.
Lucky Charm is not good. The extra items aren't worth all the points. I had it maxed on my 1st playthrough, so I know by experience.
In the first map, it's simple to guess enemies' weaknesses, but later, it is not. I like Loremaster for this, it improves the strategic aspect of fights.
Tier 5 spells are underwhelming/bad. I like to maintain Pyro, Geo and Aero at lvl3, Witch at lvl4 and Hydro at lvl5 (but my parties have physical attackers). This gives enough slots to have all the good spells without penalty. But since you have 2 mages, you can have 3 schools maxed on each and experience all the spells yourself.
You won't be able to effectively combo geo+pyro or hydro+aero if they're in the same character. There's not enough AP in the beginning for a single character to combo them in one turn. Enemies will move out after a turn.
