As for my wizard, don't i get an extra spell slot/point with which I can cast a spell, pr. each round number of int (like 16, 18, 20)?
You don't
learn an extra spell with higher int. You get to
prepare an extra spell, so you'll have 1 more of your spells known available for immediate casting.
You can't cast any more spells per day either - you'll have the same number of spell slots regardless of your Int.
As for the feats you mentioned:
Lightly Armored: Not Terrible, but Not Great. - I would say you'd be better off using the Mage Armor spell (1st level spell; sets AC=13+dex) over Light Armor (Studded Leather sets AC=12+Dex) since it gives more AC.
-
However, BG3 has plentiful magical armor, and Studded Leather +1 (or +2, or +3) would provide equal or better protection than Mage Armor.
- Additionally, some helmets require Light Armor proficiency, although honestly as a spellcaster you probably wouldn't be wearing those anyway...
Skilled: A fine choice, until/unless Larian changes BG3 so that party members can join in on dialogue checks
- Your sorcerer, with their high Charisma (and because they're your PC), is likely to be the Party Face and do most of the talking. Thus, it'll be good for them to be proficient in more skills.
Weapon Master.
Would Not Recommend.- I assume your sorcerer has a 12, maximum, in strength? Or a 14 maximum in dex? These are relatively low scores and will remain so throughout the game. Thus, you won't be especially effective with weapon attacks.
- Using melee weapons would put your (low health and low armor) sorcerer in combat adjacent to enemies, resulting in them getting hit often and going to zero HP and/or losing concentration on spells.
- The few spells that DO work well with melee weapons are probably not going to be added to BG3. Additionally, there's a 2nd level Sorcerer Spell (Flame Blade) that creates a blade that deals 3d6 fire damage - more than a normal weapon attack.
- Ranged spell attacks are just better than ranged weapon attacks. Your cantrips will surpass any longbow/crossbow attack you can make at level 5+, and your leveled-spells are always strictly better than a bow attack.
