sorry about your luck, the reason the game freezes up a lot(especially when your far into the game and your save file is around 8-10MB) is because of the software used to make the game, Gamebryo. For some reason, either because of the extra features of New Vegas(like multiple endings, modified weapons, crafting and recipes, etc) or because of half-assed programming, issues are far more present in NV than Fallout 3. Things like the Broc flower glitch are scripting errors, and can be fixed through a patch, however we haven't heard any news from Gstaff that they're at least working on it, so it could be awhile....
Unfortunately, there's nothing that really fixes this. I have a thread titled "For people with freezing issues" in this sub-forum, which helped some people, including me, with crashes/freezing. Please note that it doesn't help everyone, but there's nothing to lose by at least trying it. a bonus is if you choose to restore your file system you'll clean up any corrupted files that are stored on your system.
For things like bugs and glitches the best you can do is make a lot of multiple saves instead of overwriting your previous one, so if there is a scripting error you can go back to a previous save and re-trigger the script(for example, you go to talk to an NPC to trigger a quest from them, but the only speech options are "goodbye". reloading a previous save from an hour or two before may fix this.)
Some good news: Bethesda is discontinuing using the Gamebryo software in future titles. but that doesn't really help the people who have purchased this mess.
Hope something works for you.
Also, to safely turn off your system after a crash(or freeze, they're the same, really) just press the power button a single time and patiently wait for the system to turn itself off. It may take a couple minutes,I've had to wait about 10 minutes once for it to turn off, but it's the safest way to do it. your system is completely unresponsive after a crash, so you wouldn't be able to bring up the XMB or the black screen that comes up after holding down the PS3 button on the controller.