It's a 15 passenger van

trying to turn off Maintence light

If my heat is turned on the brake warning light comes on the blower does not work,if I push a power window button the brake light comes on when I put it in reverse the brake light comes on where do I look? Is this a ground problem?

How can I improved my gaz mileage, when it was new I use to get 17, now with a rebuilt engine I only get 10

i did take all the scrues off but it looks like the oil pan it´s stuck it can be some kign of glue or something but i want to be sure.

just install installed a used gas tank. wondering if i have to prime the line because it won't start.