Hi again SM,
Gail hopefully ansswered about the hotshoe to your your satisfaction
About battery packs, there are two types of power sources for most cameras:
1-AA batteries
2-Lithium-ion packs.
The AAs are convenient, easy to find, and you can get rechargeable ones easily (I would suggest Sanyo Eneloops or Ray-o-Vac Hybrids, as those keep their charge M longeer than otherr rechargeables). On the long run, you're better off with rechargeables instead of disposable, but Lithium disposable AAs can lat for much longer than any other type of battery. Cameras that use AAs usually only cme with cheap disposables, so you have to purchase other batteries before long.
The lithium-ions are proprietary, meaning that they fit one specific camera (or a few different cameras from one brand, sometimes). they are lighter than AAs for simiar performances, but they are more expensive and harder to find. Cameras using these batteries usually come with a charger and rechargeable battery.
So, in short, any camera can use rechargeable batteries, either proprietary or AAs. A higher number of AAs in the camera will mean a heavierr camera, but a faster flash recycle time. Regarding Li-Ion batteries, the higher the voltage the faster the recycle time, usually. You can find good databases for various cameras at
www.dpreview.com.
I hope this clarifies things.