Some questions about an AVR based oscilloscope.

[bobleny]

So, I am looking at this project here:
http://www.serasidis.gr/circuits/AVR_oscilloscope/avr_oscilloscope.htm

I am not actually interested in building an oscilloscope, I am more interested in building a 120-240 vac 50-60 hz signal analyzer. I would like to build something for monitoring the power being fed from the electric company into my house in as close to real time as I can get (obviously it takes time to convert and analyze the signal).

The project won't work for what I want it to, but I feel that it is not too far off.

My questions are...

Can I increase it's voltage range to meet my needs, or do I need to use a transformer to lower my line voltage?
--> If I use a transformer, is that going to significantly alter my signal?

The probe circuitry uses an amplifier. Would I really need an amplifier in this case?

He says he increased the sampling rate from the last project. Is there any way to actually calculate what that rate is?

Thanks!