Even the old warded rim locks that adorn Victorian interior doors and that would yield to a hair grip usually had screws through a plate over the door edge. If it mounts on the surface of the door, it is, by definition, a rim lock.
More important is the strength of the door frame and the latch plate fitted to it. That will usually give before the door or the lock or, if you have the recommended pair and a half of 100mm long metal hinges, the hinges.
Not necessarily, although it is more secure not to have a thumb turn on the inside.
Mine is about 3mm longer than the Yale rim lock key, because it has an extra pin in the cylinder, but is otherwise similar in size.
Generally, you need most security during the day, particularly when the house is unoccupied. At night, I use a BS 3621 nightlatch and some very heavy duty draw bolts. However, the safest route out of most houses in a fire is through the window; hallways are easily blocked by smoke. An adult can hang from the window and only have a relatively small drop, while children might benefit from a flexible window escape ladder.
Colin Bignell