I want to start playing some slide

So long as the action isn't extremely low you should be alright. The key is to balance action with the right slide (i.e - heavy slide with high action will work, but for low action a lighter slide would probably be better). I'm happy using a glass slide on my electric, which has somewhat low action.

You also don't need to press down at all, the weight of the slide is plenty enough pressure to play, so that's another thing to be aware of.

Lastly, muting is important, for example if you use the slide on your pinky, you can mute string noise with your left hand by resting the other fingers you aren't using on your left hand behind the slide (if you use your ring finger, use every finger except the pinky to mute). You can also mute with your right hand by resting the underside of your palm or thumb on the strings while you pick. It takes some practice but I think you'll notice those noises start to disappear if you work on your muting technique.

(was writing this while SteveO was -- a lot of the points are similar)

you need to develop just the right touch for slide playing. sure, it can be easier if you raise the strings, but in the long run, many of us like knowing we can just pop on a slide and switch from fretted to slide on nearly any guitar. the chattering you describe is due to either not enough or too much slide pressure and/or possibly too much picking force. gotta practice that touch -- and unless playing on raised action, think light in terms of slide contact (not so much a force or pressure) and pick or strum lighter as well. there are times when all that chatter, clatter and dirtiness sounds great, but work on that after you learn clean control. muting behind the slide, as well as palm muting are important techniques to control chatter and buzz.

keep in mind that a little slide goes a long way, so if soloing or filling, you usually won't need to play so many notes, but will be making some of those you do play really sing with sustain. so concentrate on making fewer number of notes sound good. also realize that you do not need to slide into every note or use heavy vibrato all the time. the timbre of a slide note varies with touch, string choice and position on the fretboard. you will learn to work this as you develop touch sensitivity.

so: work on a light touch and muting. also try the slide on different fingers -- keeping in mind that you will likely want to leave at least your index finger free to do muting, fretting and string pulling behind the slide. experiment with slide masses and materials. we don't all like the same thing. heavier is usually more difficult for noobs, as is makes touch control a bit hairier. different materials seem to work better on the various types of strings. but you should experiment with that to determine what you like to feel and hear. a good place to start is with one chrome and one glass slide -- and maybe a brass. later, try out the "real" bottle necks, ceramics, hybrids, Sears sockets, Coricidin bottles and all the others.

for electric guitar: try your setup both clean and with 'dirty gain'. later, you may wish to add a compressor for clean sustain. lots of rock and blues players work with really pumped gain to get that 'infinite' sustain. requires good touch control.

and: listen to these great slide players: Sonny Landreth, Lowell George, Bonnie Raitt, Duane Allman, Robert Johnson, Derek Trucks, George Harrison, Jeff Beck, Leo Kottke, Muddy Waters, David Gilmore, Ry Cooder ...