[EasyHangIt95]

Hello I have read a lot of posts about SOME of my problem. I could really use some tech help. Please!
I have a 1995 K1500 GMC z71,5.7 stepside. It was sitting for 14 months but runs ok. I bought it because of the way looks. I havent seen too many here in NYC. All of this was not working when they dropped the truck off.

A)The Odometer, Speedometer, tach and prnd don't work. I
I have replaced the VSS $82.00 no change.
People have said its just a ground wire. OK, But where?

B)I was having a problem with the brakes so i changed all the way to the hoses including MC. The bakes seem to be fine until i have a slight down grade to a stop. All of a sudden the brake pedal goes soft then it feels like someone is hitting the brake pedal with a hammer real fast! The truck stops but what the heck is that? It was quite scary.
Oh . I forgot one thing. The ABS light was on. I checked the front ABS sensor and the wire was broken so i soldered it. The ABS light then went off for awhile.

Here is the main question: Can all this be related to just a little stepper motor in the instrument panel that tells the computer how fast your going? If so, The odometer could be fixed and the speedometer but what about the Tachometer??
I realize this is a lot but my kid's think daddy can fix anything and its been two weeks! I didn't want to take apart the dash for no reason But i will if some one can guide me.
PS: I have been working on cars since i was 15 and this is killing me.