4) Every time i place a thief's trap(i've tried imoen or protagonist) the thief somehow gains a shapeshift ability and can morph into a jelly, gnoll and other lower-level creatures.
Hmm... I just noticed I get this too o.o
You can role-play and say thieves are masters at deceiving people and thus have really, really realistic disguises :3
Ain't that one of SCS 19 / SCS 19 II doings? At least recommended install without them does not produce the symptoms.