According to thie following article, it is 5000# http://www.johnholt-chevrolet.com/testdrive-review.aspx?year=1996&make=Chevrolet&model=Blazer
That would be 5300#
That really can't be answered. Are they stock? What are the sizes of the tires? What type of s10? What type of blazer? An s10 truck's tires should fit an s-10 blazer. A s-10 truck might be too small...
That would be a 4L60E automatic.
Check the fuse, then the bulbs, then the brake light switch.