Like you currently, I went through the same progression to "lightitude" a few years ago. I was also coming from a lifetime of outdoor experience, working in both outdoor retail and experiential education. A big part of the transition for me was mountaineering; self-supported trips required a critical eye when it came to what gear made the cut. A rock rack, screws, deadmen, pickets, ice tools, ropes; that stuff weighs a ton, but you're not climbing anything without it! Anyways ...
Something like the Gregory G-Pack (I still use mine) or maybe the REI Cruise UL would be a good place to start. Not too expensive, still has a good frame so it can support a decent amount of weight while you make the transition, and pretty widely available. If you wait a couple of months, the new REI convertible pack looks pretty interesting, the removable frame will allow you a frameless pack when your baseweight is really light, and a frame for heavier loads.
For a tarp, I really like my GG White Lightnin tarp. There are lighter options, but the webbing makes setup pretty quick if you're super-experienced with tarps. I also really liked the bias-taped ridgeline seam; I never worry about too much tension on the ridge seam! Plus, when you get really comfortable pitching tarps, you can just cut the webbing off and make some small loops. I'm about to do this to mine, and I'm going to add some linelocs to keep setup and adjustment simple.
The options mentioned above are also relatively inexpensive; the packs are under $150 and can be found on sale often. (I bought my G-Pack for $75 from STP) The tarp is about $125, I got mine for $90 on sale if I remember correctly.
Good luck on lightening up, it has made my trips so much more enjoyable. Your in the right place; this is the best online community in existence. See you out there!