welly-well-well...
yeah ext3 (It does journaling so it does mean a lowered lifespan for the sd card but the upswing is if there is a crash or error the system should reboot and repair itself automatically...you just sit back and relax)...
you can do ext2 (it doesn't do journaling so it means increased lifespan for your sd card...downside is if it goes wonky-wonk and crashes....you fix it yourself)
so it is a matter of personal pref.
As far how to...there are a number of threads for the nxx0 ...some may be for the n8x0.... some the n900 ...some threads may refer to both devices...methods on n8x0 essentially are the same on the n900 with a few differences in proceedure.....this'll get you started on the topic...here are a couple of links I myself have found helpful ...take your pick...I'm sure there are more.

http://talk.maemo.org/showthread.php...016#post216016
http://talk.maemo.org/showthread.php...ighlight=Links
http://talk.maemo.org/showthread.php?t=89388

by putting easy deb on it's own rather enlarged partition...say on your microsd card...anything goes weird..no problem...it isn't like "installing" a proper distro that can have an impact on your device....after all it is easy deb running on top of your maemo...and it is isolated to your card as a topper...and it should run faster and you should have enough space on your made partition to build the terminator A.I. program of your dreams...(oh sorry wait...that's Dave's dream...
Not that I'm mocking ....I have no desire to intimidate a killer A.I. that sees this post 20-40 years in the future...I didn't mean it! Honest!)