Wise statement. Realistically, you don't have to overclock much at all to get 720p. I seem to recall several testers of it were running 800Mhz. I personally run 500-900Mhz, but locking is a rather silly concept. Btw: even locking in general still leaves two levels, one of which is 0, or the resting state. But locking at a high rate means one rogue widget could suck your battery and turn your phone into a pocket warmer.

As for overclocking, the simplest way to do so is use the kernel-config command. Look at the documentation page for it for options, set it up the way you want to... test it out, and if it all seems happy, save it as a profile and set that profile to be the default one. You can do all that via command line just using kernel-config. Or, you can load one that's already done for you, like the dsp config.

The only "speed up app" I trust is swapolube, for the simple reason that it has a button marked "default" that restores the kernel's default settings. It also shows you what it's doing, and gives you all the proper internal names so you can look-up what the value tweaks and why you may or may not want to touch it. Any app that lets you reset what it's done in a clear and transparent method is generally good IMHO.

Keep in mind though, any time you install anything, you're taking a risk that it can cause instability. The less you know about it, the more likely it can screw things up. If you don't know what it does, or how it does it, best to stay away from it all together, because you probably don't need it anyway.