IWD2 rules aren't as well-suited to soloing as in BG2: in BG2 a soloer would level up much faster than a party, while in IWD2 you end up losing the advantage because of the Challenge Rating system, but I heard it's still doable (even without cheating). An Aasimar Paladin(2) -> Sorceror is probably the easiest character to start soloing with. Stat-wise, max out Strength, Constitution and Charisma at the expense of Intelligence, increase Charisma when you level up. Start plaing like a plain warrior (wear the best armor and shield, don't use spells except for precasting Mirror Images) until you can learn Stoneskin, at which point you can use that, Mage Armor and Mirror Images to absorb the damage, while hitting your enemies with spells and swords.
The IWD2NPCs aren't minmaxed, but you don't really need minmaxing (or using cheats) if you go with a full party.
To alter your stats you can use DaleKeeper 2.