Hello and congrats on your plasma decision. Plasma is the optimum PQ technology these days, until SED displays make it to the mass market---if ever. DLPs suffer from color inaccuracy and essentially non-realistic PQ. The single color wheel DLPs by definition can never be accurate and the newer LED displays, while better, still dont make it. LCDs work on light bulbs so a decent contrast ratio can never by generated, as a shadow detail and shardes of darker colors cant be reproduced by a light bulb ( ie off is off). Their refresh rates are indeed a tad too slow , although improving. Meaning motion artifact will occur.
AS far as brands, I find Pioneer to be a better display in lighter conditions, such as a room with daylight. Panasonic is the better display in a darkened room and over time, their is less viewer fatigue with a Panny display. Hitachi is excellent too, with NEC in fourth place in my opnion. Some folks fell NEC is a much better display than given credit for. While I dont agree, I thought it worth mentioning. Sony discontinued their plasmas; they had absolutely disastrous QA problems; Samsung falls in to the next group followed by the Vizios, Maxents, Phillips, Gateway, and Zenith products.
Fujitsu used to have absolutely the best Plasma but hasnt had an update to their famed AVM-2 processor in years. Reportedly new tech coming out soon. Still a great display however! Very expensive.
AS far as power conditioners/line consitioners--hit and miss effect--often based on local current conditions really. Your PQ will be drastically more affected by a good calibration than a power/line conditioner. Surge protection however is a no brainer and I am not talking about a 10 dollar power strip either.
DVD players-- well--are you planning to watch Hi Def DVDs or standard def dvds? Assuming standard def-- you want excellent 480P players. If you get an HD-Lite display--ie 1366 x 768 res or a 1024 display, you now have to consider whether you want to upscale at the level of the DVD player or the display. Remember OPPO DVD players cannot de-interlace over a component connection as an FYI. At 12.5 feet, our eyes cannot really discern resolution differnces so easily, so keep that in mind. hometheatersecrets and Kris Deering and co do their famed DVD shootout where you can compare myriads of DVD players in total score but more importantly in written test result form too. SO you can see strengths and weaknesses of most DVD players out there. Check that out. A lot of the best 480P players came and went a few years back as much of the newer emphasis and R and D dollars have been placed into HDMI connectivity and Hi Def DVD players. ie; law of diminishing returns over time.
good luck.