So your priorities seem to be the following:
3. Format longevity
No problem, go to ebay, buy a used HD-DVD player. You'll probably get quite a few HD-DVDs to boot. Since you want a format that has the most media available to rent, and, I'm assuming, will look its best. I would go for a Toshiba HD-A35 or Toshiba HD-XA2, as they both upconvert the best for the lowest price, and you'll also get a taste for what HD media can do with the few HD-DVDs you'll get with the player. Those two players I mentioned will also play regular dvds, and make them look great. If you decide later that you want to go Blu you can move your great, yet inexpensive HD-DVD player to another tv, and will have lost nothing. You may find that you want to even purchase a few HD-DVDs, and you can still do that for about the cost of renting, just know that the selection will be limited.
Read more in the HD-DVD and BluRay forum for deals, available titles, where to get them, and upcoming releases for BluRay. Don't forget to use the HDMI cable from your player to the receiver and then another HDMI from your receiver to the display to get the best audio and video. Buy those cables from a forum sponsor, you can find the links at the top of the forum page. The HDMI cables from them are of the same, or better, quality than Monster cables, and much less expensive.
Enjoy your journey.