Originally Posted by
JiveTurkey
#1: If I understand question 1 correctly, I do not think this is a mis-adjusted rear derailleur. It's just less than ideal form. It sounds to me like you are using the small chainring/small cog combination. The chain may be falling off the inner chainring due to insufficient chain tension and/or cross-chaining. In general, you should not use this gear combo (nor big/big).
Sorry, I don't see how chainline causing a chain jam on the lowest cog doesn't fit under "misadjusted RD". This is what the high limit screw was DESIGNED to do.
If you want to play the what else can cause this problem assuming nothing is working properly/not bent/compatible then you better start an encyclopedia.