1. under normal ops, it shouldn't.
4. The cluster (do correct me others if this is wrong) has the immobiliser build into it, as when u do a swap to highline u have to backup the keycoding, so this should stop the problem. HOWEVER it could be something else, i.e. the reader part (not sure if it in the barrel or some were else) is the battery going on the key, being pressed if ur jean pocket all the time.. Is it going out of sync, being pressed when out of range too much..
5. Yes, though i think u need VAG commander (or what ever it is u use to code the cluster) and you must notify ur insurance company that u have disabled it !