You may want to put the
slide idea on hold for a while. Remember, a lot of the tone comes from the usually thicker strings. I believe Kirk has his strat set up with a heavier string gauge since he uses that a lot for slide work. (somebody correct me if I'm wrong!)
A thinner string will work, but , to me at least, the tone is a more shrill, almost whiny tone and can be unpleasant at times.
As for fretting, you probably know, the slide itself stops directly above the fret for the note. As for switching back & forth, watch a couple of Kirk's videos on slide and you'll see him switch back & forth....but that takes lots of practice.
If it was me...If I had a few weeks before the show, I might try it with lots of extra slide practice. If it's sooner...I'd focus on getting my amp settings correct so I could hit the pedal, jump from a rhythm setting, to a bit louder lead, then back and make sure I nailed a normal lead. On the last vid or two, you played some nice stuff, Jess, make it a bit stronger and then the next time, maybe try the slide
But hey, that's just my opinion, FWIW HA! Good luck !!