The remote head is a nice little unit, but it is also expensive for what you get out of it. Whether it is worth it or not is tough to answer. I believe it is worth it if you plan to permanently install it somewhere, but it may not be worth it if you're only going to use it temporarily. Although as long as you keep it in "like new" condition you could always sell it on eBay close to what you payed for it (or possibly even more, since many people still don't know they are available new from ScannerMaster).
Regarding power, as already stated by Garys, you do need to provide power to each unit separately. To expand on that I can tell you that the RH96 comes with a cig lighter power cord (the same cord that comes with the 996XT and other mobile DMA scanners). For temporary usage, the cig lighter cord will work fine for you. If you want a more "semi-permanent" (hard-wired, but removable) installation you could always cut the cig lighter plug off and tap into your fuse box or wire to the same power source as your scanner.