Exploding my Mac with the best of intentions

So, today (April 12, 2012), I became aware of recent vulnerabilities in Safari. Since I still occasionally use Safari (being the vendor default browser on my main Desktop), I decided to apply Apple's security patches. Turns out that these security updates are not available to Snow Leopards like myself. Mountain Lion has just arrived and does have the fixes I am looking for. It's inexpensive and easily downloaded. $20 and a few downloaded gBs later, I find out that Mountain Lion requies a new version of Xcode developer tools. In fact, it turns out that leaving the old version of Xcode lying around is causing problems. Then it turns out that Mac Ports no longer compiles several utility libraries I am using. Switching to homebrew does improve my prospects, but now there are issues with the mysql install, which I am relying on for my rails app development.