To avoid damaging your buffers when stacking them, you can solder pins on alternate sides of the chip, to avoid heating the chip on one side too much. And, you may find that you need to stop every now and then. The chips can get fairly hot when stacking them like this, if you're quick with your iron like I am.
The solder just wicks up and down the pins and into the gap between the pins, so it's not much work at all to solder things. The hardest part is the first pin, because the chips often want to fall apart. Once the first pin is soldered, it all stays together nicely.
There's new info on buffer stacking in the META42 article, so re-read that section if you haven't done so in the past few days.
As for EL2001 vs. EL2002, I haven't compared these rigorously, but my vague impression is that there isn't a large difference. I mainly use EL2002s when I need the additional bandwidth, such as when I have a fast have op-amp like the OPA637 (80 MHz) in the amp. I also use them occasionally for amps with wall power only -- just for a cavalier "why not?" sort of reason, not because I have a really good reason.
