OOC Chat
The points you're adding to the skills section are actually counted as bonuses. The GM would decide the difficulty of a particular action (% based) and you would add any bonuses that apply. So if you are given a 50% chance to succeed at say, tracking a hunter in your area, and you have a +15 in tracking, then you technically only have to beat 35%.
As for spending them, it's and/or. You can spend them generically or you can specialize. So you can have a general skill level in build/repair, or specialize in mechanical, or put points into both. How this applies depends on the situation. So having points in generic build/repair would give you a bonus to figure out, say, something wrong with a 4-wheeler. But you would probably need a good bonus in mechanical to fix something like a busted carburetor.