To my knowledge most have settled for 250mhz as minimum. You will have a better flow on 500mhz but a little bit more batterydrain (my opinion).

The most important thing is not to leave the charger in when it is done (i.e. green led). In other case charge when you have time. It will not improve if you run it to dead.

By skipping frequencies you are avoiding them. It will be on less step to take and it will use less battery. You need to make a custom profile by "kernel-config save myconfig" and then run it by "kernel-config load my config".. to edit you can open it with "leafpad /home/user/.kernel/myconfig" (need to have leafpad installed)

The best way is to use the "kernel-config lock <freq>" and try them one by one.

No other programs are needed. Though some script could be useful.

Programs that give you control over your connections are good. It is better to run 2g than 3g and you will not always need wifi. BatteryGraph. Try keep away from bluetooth. Don't put too much widgets up if not needed. Do as much as possible in the xterminal. The commands "top", "kernel-config show" or "df -h" in terminal is mostly better than Conky.

My phone hold battery 48h+. Don't actually know anymore because i always find time to recharge before it depleats.