hmm. perhaps this isn't really the best forum in the world for analysis of dnb/jungle.
dogsonacid could be a better place to go, but i haven't really checked out their forums so i don't really know what the vibe there is like. there are other, more localised forums as well (eg. sydneyfriction.com and the dnb section of inthemix.com.au are my local ones).
i've never really liked ishkur's guide, just because i don't like splitting things into genres, sub-genres and so on that much. and electronic music is especially prone to doing that. it is a good starting point, though.
ragga and ragga jungle are two quite different things. plain ragga has more to do with reggae, ragga jungle is a lot more uptempo, and a lot of the stuff being produced today does sound quite electronic -- use of things like cone filters, timestretches, snare rushes, and so on.
you're right, jungle does sound quite "ambient", since a lot of the harder styles didn't really take shape till the mid to late 90's, so in comparison it does sound a bit lighter.
drum and bass pulls props from all over the place. "liquid" stuff was quite popular in the early 00's (check out some of the plastic surgery compilations from hospital records for a good intro to that style), drawing influence from funk and jazzy stuff. after a little while it started to get very cheesy. ltj bukem pretty much owns jazzy drum and bass though -- and he's good enough at it to not make it cheesy or whatever.
if you want to find out about the distinctions between styles, time periods and artists in jungle/drum and bass, the best thing to do is start going to gigs, listening to mixes (try
dnb-sets.de, they've got heaps of stuff there), buying albums, and reading forums or magazines (
ATM and
knowledge are the two best-selling ones. both from the UK, unsurprisingly). there's also
BassDrive drum and bass internet radio, which plays a fair range of different styles.
at the moment, i'm into what you call "throwing pots down stairs" drum and bass
-- stupid stuff that often verges on unlistenable. trying to get people to like this music straight up is like trying to sell textbooks on fluid mechanics on a street corner -- it's not something you can get into straight away, more of a sort of progression. but i used to be into a lot of the jazzier stuff. i reccomend checking out stuff from labels like full cycle, hospital, and good looking records for a start.
the MSX radio from GTA is actually a mix CD from another UK label,
moving shadow. they tend to release "techier" stuff which can get hard/loud sometimes, but always flows/rolls along quite regularly at a danceable pace. they are also worth checking out; that MSX mix is pretty representative of their sound.
stay away from labels like renegade hardware, evol intent recordings, barcode, outbreak, etc... unless you like pots-and-pans dnb
anyway, i better stop procrastinating and do my assignment. hope that helps, anyway...