The power plate I use is quite big, I would say about 1 metre by 1 metre (sorry, not sure what it is in feet)
I think this is the one I use:
There is a whole lot of exercises you can do on it, I found the ones that are sit up like (they call them ginache here in Switzerland..) are the best, my sides have really firmed up. Also there are some good leg exercises..
I do 35hz for 1 minute (with the massages on 50hz for 1 minute), but some trainers do 40hz for 45 seconds. The 1 minute is harder than 45 seconds, the extra 15 seconds can be torture.
I also can't stress this enough.. I use a trainer at the gym and would not start using it without one (I have had about 20 sessions so far, and now I may do it on my own, but the trainer is good for making sure you do the exercises properly..), the machine does not discriminate on which muscles it vibrates, and above all, always keep your joints bent!! If not.. it is a lovely sensation whith your legs straight and you can feel your brain bouncing in your head... Also make sure you get a trainer that knows what they are doing.
I am not trying to put you off, just be aware that the machine is very powerful. They say you should not do more than 15/20 exercises per session, and honestly, that is all you need.. The massages are the best, my cellulite has gone thanks to them..
Hope this helps