Well, each chip is different on where you put it. Som have you solder a switch on the d0 connection wire, others have a spot on thier chip left for you to put a switch on. The matrix has a boot combo on it to turn the chip off, which you will have to look up. Im not sure if you can install a manual switch or not.
The X2 pro has manual switchs which are explained
here and the X2 Lite has a manual switch which is explained
here.
I guess the older chips and lpc mods using the SST chips only need user installed disable switches. So, if you get the x2 pro/lite (with pogo pin adapter) or the matrix, you will not need to solder anything at all, not even switches.
The chips I mentioned above are probably the most well known chips for the xbox and you will be luckt to find a place that is not sold out.
For HDD's, the 7200 or 5400 should be fine. Seagates are recommended.