I don't know what blumlien....
Blumlien is a microphone technique that uses two Fig-8 mics, crossed at 90 degrees. It can be a very good mic configuration in the right scenario, but that scenario often doesn't overlap with the scenarios that we "tapers" generally find ourselves in. However, given the right scenario, it can be a great way to run the mics.
and four mics sounds scary....
don't worry about 4 mics yet.
How would I power a pair of these? I know it needs p48...but how? a ps2?
there are many ways to provide phantom power to mics. A Denecke PS-2 is certainly a viable option, although not the only. A big question is what gear you are planning to run behind the mics. Outboard pre-amp? or straight to an all-in-one recorder? most outboard pre-amps will also provide phantom power. but without a budget, it's hard to recommend something. a Beyer MV-100, a Sound Devices MP-2, or an Edirol UA-5 would all be on the cheaper side of things, Aerco MP2, Lunatec V2 or V3, Neve Portico 5012, Sonosax SX-M2, etc, etc, etc all provide phantom power as well. Because you're getting started and looking at less expensive mics, my guess is that you'd also be looking for other cheaper options as well. but maybe you're also thinking about going straight into a recorder and using the deck's internal pre-amp and A/D converter. a recorder like the Edirol R09 does NOT provide phantom power, while something like the Fostex FR2LE or the Marantz PMD-660 or PMD-671, Tascam HD-P2, or Sound Devices 722 could all provide phantom power and you wouldn't need any other outboard gear.
the pre-amps and decks listed above have a wide range in price, quality, and size.
What I'm getting at is without an idea of your budget, and without an idea of what other gear you're looking at or considering, its hard to make a good recommendation.