1) If you attempt a pass and it results in contact that causes the other car to spin out on track, go 4 wheels off, or being so badly damaged that it can't finish the race. This should be an automatic stop & go penalty, or (if the incident happened on the last lap) an equivalent time penalty (probably 30-45 seconds at most track). No exceptions, no analysis of intent, no "it's just racing." If the contact was deemed intentional or the incident was particularly egregious, then we can have the lovely little hearings & figure out even worse penalties.
2) By the same token, people shouldn't be allowed to block like complete idiots either. You are only allowed to turn in once. If there's another car alongside you (and by that I mean the front wheels of the overtaking car are next to the driver of the overtaken car) you aren't allowed to drive all the way to the apex curbing. If you do that sort of thing, you automatically get the penalty described in #1, because you're just as dangerous as the idiot who decides to dive bomb you from 10 car-lengths back.
3) You should never be allowed to turn where there are no turns. The only acceptable reasons for chainging course on a straightaway are in preparaton to pulling off the track or to perform a drafting pass. Weaving around because you botched your exit on the turn should never be acceptible, and the guy behind you should be legally allowed to kick you in the nuts after the race.
I'm all for competetive, close racing. What I'm not for is the hockey-game-like antics that go on at most club races these days. I can train a chimpanzee to play bumper-cars. It takes true skill to pull off a clean, competetive pass. If I want to race somewhere the "chrome horn" is considered standard practice, I'll go back to short track racing and spend far less money doing so.