1. Whenever this topic comes up (often!), people always warn about airlines refusing to short check baggage; while my data sample is not large enough to be of statiscal significance, I've never been denied this request
-that having been said, I don't recommend banking on a short check

2. Insofar as being rerouted via a different city is concerned, I was under the impression that passengers generally have the right to accept/deny new routings (perhaps this isn't a legal right, but we all have unique quicks when booking flights, and I see know reason why airline staff would want to press us on this)

3. NEVER announce hidden city aspirations to airline staff. Doing do could possibly compel an otherwise indifferent agent to elevate your case to ticketing (not because they want to, but because you've dropped an issue in their lap that they are obligated to follow up upon via preset protocol)