Ok, here you go:
Ram varies by socket, LGA1156 and LGA1155 use dual channel.
LGA1366 uses triple channel.
The practical difference is that if you need between 4gb and 6gb for your daily stuff triple is better as you'll have three 2gb sticks without loosing performance.
If you put 3 2gb sticks in 1155/1156 you are forced into single channel ram mode, which is half the speed of dual channel.
Speed wise, dual and triple are quite close in everything but memory benchmarks, it's not an issue.
CPU wise:
The "K" cpus have unlocked mulitpliers, on 1156 and 1366 this isn't a very big deal, it makes OCing a bit easier as you don't have to balance ram and qpi and uncore along with cpu core while changing bclk, but it's not really that hard to do.
On 1155 (sandybridge) this is very important as the multiplier is the only way you can overclock!
The non-K chips either have four extra multipliers for OCing (i7s) or none (i5, i3). That means for a stock speed of 3.4ghz (say a 2600), you can only OC to 3.8ghz, no further.
With a K chip, you can use up to a 57x multiplier, for 5700mhz. Now the chip may not actually be able to run there (in fact, few will, if you get one that will sell it to me immediately!), but
all of them will do 4.5ghz bare minimum with 24/7 safe voltages.
Now, that said a 2600 at 3.8ghz is faster then a 1366 core i7 950 at 4ghz, so that's probably OK if you aren't planning on benching.
Here is what I would tell your son:
"Son, buy sandybridge. I know it's impossible right now due to the recall, but this is the time to learn patience, it will be worth it."
"In the mean time, check out overclockers.com as they have by far the friendliest people, including this Bobnova guy that showed up on FK recently"
"Once you get your sandybridge setup with a 2600K, I expect you to OC the balls off it and join the overclockers.com benchmarking team to help them, and bobnova, dominate the rankings"
Or something like that
The "best" varies a lot based on what you're doing, and your resources.
For instance, right now I have the "best" intel chip, a 980x (ok 990x is 2% better, sue me), it beats sandybridge in everything
IF I cool it with liquid nitrogen. I cannot do that as it costs a ton here, I cool with dry ice. On dry ice, the 980x cannot get high enough to beat a sandybridge chip, so for me the "best" cpu is a 2600K.
On air, it's no contest, the 2600K OC's further on safeish voltages AND is faster clock/clock.
