You typically don't chord much when playing slide, apart from the I-IV-V chords you can form with the slide barring straight across the strings. When you play with the instrument on your lap or on a table, you usually hold the slide in your palm. If you play in normal position, you wear the slide on your ring finger or pinkie, so it's not usually available for chording, though if the slide is on your pinkie you can form three-finger chords easily enough with the other fingers. Also keep in mind that, when the slide is in use, at least one of the other fingers lays behind it on the same string(s) to keep that section of string from also vibrating and producing a raucous buzz or clatter.
A hallmark of slide is the vibrato or wobbling of the barred chords. If you combined the slide barre with fretting (say, by wearing the slide on your index), you couldn't apply that vibrato effectively (and the string portion behind the slide would make noise).
The best slide keys keep the barre IV and V chords in close proximity. Most commonly, the I chord is low (the open chord or the 2nd fret), the IV is five frets up from I, and the V, seven frets up. If the I is played across the 2nd fret (key of D), you can also play the "Mixolydian" bVII major chord at the open fret and wobble the I chord (which you can't do when playing the open strings), but your open strings are less useful in D, particularly for droning the tonic and fifth on the 4th and 3rd strings while playing slide melody. It's all trade-offs.
For your well-known chord shapes, the 1st string would have to be played 2 frets higher (and remember that you only have three fingers available for chording) or you'd have to choose a different voicing and/or position. The resulting shapes correspond to those used in standard banjo tuning but transposed up a fourth, since that tuning is G-based, so if you want chord charts, there's a good source—remembering that you need to transpose names and that you're largely limited to three-finger chords. Sadly, some very common chords, like dominant 7ths and minors, become rather awkward. That said, often a three-note chord will suffice, if you're fingerpicking or adept at omitting the top or bottom string when strumming.
Using the slide straight across the strings or at angles, you can form wobble-able dyads (two-note "chords"), typically a melody note and a harmony note. You may have to jump around a bit to get the intervals you want. With a linear open C tuning, straight across, you have a fourth between the lowest strings, a major third between the inner strings and a minor third between the top strings. You also have a fifth between the 3rd and 1st strings, a major sixth between the 4th and 2nd, and an octave between 4th and 1st. Angling the slide, you can increase or decrease these intervals by a semitone in each direction. With a reentrant tuning, the intervals involving the fourth string duplicate those involving the 1st (with which it's in unison, and that's why reentrant tuning is generally a bad choice for slide).
