Steve,
let me encourage you (and also all new users) to read ROOT howto's
(see http://root.cern.ch), you could find alot of answers there.
>
> 1: I've converted over a PAW hbook ntuple to a root tree. Now, how do
> I use that tree? I'd like to do histograms on it, but
> tree->Draw("event"); doesn't work, even though the variable "event"
> exists. Is there anything I'm missing?
See http://root.cern.ch/root/HowtoConvert.html
>
> 2: Is there a way to find out what variables are in an ntuple? (Could
> be very handy for transferring files!) PAW++ has such a feature.
>
provided `nt' is a pointer to your TTree (ntuple)
nt->Print()
does what you are asking for. You could also use ROOT browser
for this (see ROOT tutorials and .html above for more details)
Regards, Pasha.