in most cases when it comes to the offloading of PAX / bags, its only realised when the flight closes (approx -40min before depature) so finding out at check-in is slim, but in some cases they know in advance and will offer the below compensation if they find volunteers at this stage, if PAX need to be offloaded on short notice then before boarding an annoucement would be made to look for volunteers... usually the compensation is enough to get people to volunteer
i think compensation wise its free accomodation / travel to hotel, put on the next available flight and compensation of around £200, maybe slightly more... as for the offloading of baggage the order is generally... sporting equipment then suitcases.. its up to the handling agency and ofcourse the airline to inform passengers.. however sometimes PAX dont find out until they land, which happened on the flight inbound from FAO that i mentioned a few posts up..