Most experienced air travelers are aware that smaller, regional/commuter-type aircraft (regional jets and turboprop airliners) have undersized overhead baggage compartments that force large carryon bags to be gate checked. However, what's not so well known is that it's possible to book a flight with a mainline or regional carrier in the US and end up on something like one of these (picture by CFIF @ Wikipedia):
As you can tell, there just is no place for an overhead compartment on a plane that small. This raises the question: what happens to your carry-on bags? Do you gate-check your main carry-on and carry on your personal item? Are you required to gate-check your personal item as well?
Furthermore, when flying on a plane that small, are there general limitations on luggage that are not imposed by larger aircraft, such as weight or size limits?