welcome to the forum lurcher,
for lockpicking with a companion: press alt then the name of the thing to lockpick... i think many people had problems with resurrect companion not fighting but i don't know exactly why... maybe raze or kiya could say... apparently you have the survivor command skill for a companion, true?
maybe there is a glitch due to your computer config because i don't think that your prob with the larian armor is a well known bug... but i may be wrong... in the stats page what is your armor value when you're wearing larian armor please?
maybe there is some corrupted files... (is deleting the dynamic folder files ...Divine Divinity/Run/Dynamic... changing anything... not sure about it but anyway you don't take any risc if you do that...)
for 3 i may be wrong too but i think it's normal...
