1955 Cape Cod insulation questions

Hey folks, I bought my house a year ago and, having now experienced both of our AZ seasons (hot and not-hot) here, and seen how much it costs to keep the house warm/cool, I'm interested in trying to snug up the house a bit. I've been researching to see if it is going to be a DIY job, or if I should bring in a pro. During my research, I've found two opinions on how to insulate a desert house: 1) Keep the house and attic(s) as separate zones, as it were. Put the insulation on the attic floor to keep hot hot hot attic air from penetrating into the living spaces during hot season, and to keep the warm air in the living spaces during not-hot season. Coming from WI and NC, this makes sense to me, but... neither WI nor NC have highs of 115 and lows of 95 on a regular basis. 2) Make the house and attic one zone and insulate to keep the heat out entirely. This would, apparently, be accomplished by spray foam on the underside of the roof and the installaiton of an attic fan or two to move hot air out of the attic space, keeping the attic from reaching 140+ in the summer and keepingthe living spaces cooler. Part of their argument is that the HVAC ducts themselves are very inefficient R-wise and, by including the attic in the insulated zone, it would decrease the loss at the ducts. My thinking, though, is that I can just wrap the ducts themselves in insulation... ? And, in my head, this makes sense, but then I wonder what keeps my cozy-warm air in my house during the 'winter'? What are folks' opinions on these approaches? I'd hate to spend a lot of money on re-insulating only to find out that my nice, thick R-60 (hopefully) barrier is doing a really good job of keeping the heat in my house... in the summer. Also - currently, I have a very scant layer of nasty & filthy blown-in fiberglass (fills the space between the joists in many places, but there are also some places that are simply voids). I still have a lot of work to do in my attics (house is a remodel, and I need access to the wiring & plumbing up there) and I don't want to dig through 18" of blown-in stuff everytime I work up there. Ideally, I'd love to have this crap removed and replaced with 2 layers of R-30 batt insulation. What are folks' thoughts on that? Finally, Lowe's has a radiant barrier product that looks like it can be affixed to underside of the roof or to the rafters and that would prevent/slow the transfer of heat from the roof to the main attic area. Thoughts on this? Sorry for the long long long note. :) This is just new territory for me, so I have a lot of questions and want to make sure I get it right. :) Thanks in advance, everyone. Any input is greatly appreciated. -Shalie

I have a finished basement, the majority of which is more than 3/4 below grade. The builder installed 4-foot foil-faced batts all around the perimeter of the concrete foundation wall, some of which have been removed prior to me buying the house. My question is, do these batts serve any purpose for the below-grade portions of the foundation? I don't plan on removing all of them, but there is one 8 foot section in particular that is barely hanging on and it is in the way of a project I am doing. This particular section is all below grade and is adjacent to my concrete porch, so it seems even more unnecessary.