Even though I understand you bought a ringlight, I thought I would answer a couple of your questions and made this a new post so it wouldn't get lost since I figure most people have moved on. First, the difference between the Profoto ringlights is simple. The Profoto ringlight uses a 1000volt flashtube, the Acute 2 (made by Profoto) uses a 500volt flashtube. Aside from a minor wiring variation, they are identical and use the same accessories. BUT... that voltage thing can cost you if you don't use the correct voltage power pack. Being heavily invested in Norman power packs (its an old LA thing) and having access to a great strobe tech, I bought a like-new Acute 2. Since my Normans are 900volts, the tech was able to rewire the unit and swap out the flashtube (for a small charge - it was barely used, so he could resell it) to give me a Profoto ringlight in a Acute 2 housing. Not recommended if you don't know what you're doing. Theoretically, with the right adapter and appropriate voltage power pack, you could use any pack with any ringflash. The problem with using a higher voltage pack with a lower voltage flash is that it burns out the very expensive flashtube about 25-50% faster. So yes, the Acute 2 ringlight should work on a Acute power pack, but not necessarily a Profoto pack - check with Profoto or a good tech.
Second, (ease of use) they are clumsy to hand-hold, and since the exposure is manual only, the flash-to-subject distance must be constant or your exposures are all over the place. I use a tripod whether I'm in 2 1/4 (RZ-67) or 35mm, in which case I use a 70-210mm zoom. I also use the accessory refector which softens the light a bit, but does make accessing the lens for zoom control a little bit of a hassle. Don't know any other way though.
This is a very efficient light, you won't need more than 800ws probably (@ 100asa), although they can handle up to 2400ws if memory serves me. I personally have never used more than 1600ws, but that was on the RZ where I wanted maxmum DOF.
The attached shot was done in 35mm with the exact setup I've described. No other light source or reflectors. The beauty of the light is its evenness on the face, the falloff toward the edges, the color saturation, and that nifty edging (you have to keep the model within a couple feet of the background to get that effect). Also, when doing standing shots, keep the camera level with the chest or face on the model since there is a hot spot at the closest point where the light meets the model, then falls off. This also depends on how close you are - the closer you are, the more noticible the hot spot.
BTW, some photographers, like Playboy, use the ringlight as a fill, to kill facial shadows in otherwise lit shots. (The also use spotlights or grids). You can experient since there are no rules.
This shot of Jana Speaker was done for a calendar called (are you ready) "Babes With Balls". The whole calendar was done on 35mm Velvia with ringlight and can be purchased in stores now (don't ask, I have none to sell). I'll post a couple others if anyone's interested.
Andy Pearlman Studio