As was mentioned all BW hotels are independently owned. Upgrades are very rare as most of these hotels/motels do not have premium rooms. I stay at 50+ BW a year and receive maybe 4 upgrades a year. I usually receive exactly what I book. Status with BW really just gives you the opportunity to earn extra BW points.
Arrival gift is 250 points or a snack/water and it is the hotel's choice which to give (you don't choose). Most hotels go with the points and, as was mentioned already, those show up when your stay posts to your account. Often times the hotel forgets to award the points but they can be chased down pretty easily.
I expect you mentioned all the issues with your room to the hotel staff at the time of your stay and it appears they took no action to provide you with basic comforts. I recommend you contact Best Western customer care as I am certain they will want to know about hotels that ignore maintenance issues. All guests, regardless of status, deserve a minimum level of comfort. Maybe you should ask the BW customer care team the question you posed to the community as they will let you know "how much compensation you can get"...
BW hotels vary greatly and it is important to do extensive research to ensure the hotel offers the level of comfort you are seeking. There are many great facilities in Canada and throughout Europe (particularly the Nordic countries). The U.S. is a truly mixed bag, as is Australia and New Zealand, and more research is required in these countries.