OK you have a couple of differrent questions that are going in differrent directions.
First Where do you want to race? Is there a mini class going on there? If you are going to race mini then you dont need to be looking at brushless unless the rules at your track allow them in the mini class.
The same is true for the sedan. You only need one if thats what they are racing where you will be going. I like sedans because of the versatility. You can go TC, VTA, RCGT, or Sports GT all with the same chassis. If you do go with a sedan then your motor choice will once again be determined by the rules of the track and class where you will be racing.
Since you are a Brindle and Dalton RC is in your front yard I suggest you talk to Keith Manton and pick out a nice 1/8buggy and get a brushless conversion for it. Race Dirt.
Yes a 1/10 brushless will fit in a mini.
www.battlefieldraceway.com Racing videos at http://www.youtube.com/snoopyrc