There are magical unlock scrolls, but being rarer (can be crafted but scroll results are random), they are not a replacement for lockpicks if lockpicks will work on the lock in question.
There is no way to disarm traps or pick locks without an item.
To learn skills in another 'class' you just have to invest one or more ability points in the appropriate skills ability. The main issue with hybrid builds is balancing attributes; this can be mitigated by selecting skills that don't scale with a secondary attribute (ie Teleportation always works, even with a low intelligence character). Later in the game you can also boost attributes with equipment bonuses.
I don't recall if there is a tooltip specifically about changing skills in character creation. If you hit the Customize button a couple times it gives more detail each time.
You can max a couple abilities. If you don't want 2 master level skills, you can stop at level 4 of an ability (assuming you want one), and in some cases level 1 or 2 may be enough to give you the desired skills.
Divinity: Original Sin Enhanced Edition Character/Party GuideTactician/EE/Advanced GuideDivinity: Original Sin Enhanced Edition Character/Party GuideTactician/EE/Advanced Guide - If you aren't worried about min/maxing your characters, there are plenty of viable builds, but this gives a good overview to start with.
