I would say use one of the guitars you like-regardless of value. I know guitars can get damaged and/or stolen but when I gig, i like to have something dependable that sounds great. If you are playing real dives then maybe I am wrong but I gave up that type of gig long ago. I have always made a point of keeping an eye on my stuff and never let anyone touch it or near it.
Amp-wise-depends upon the size of the venues-get the amp that sounds best to you-playing live is what it is all about. Unless you really want a 4 x 12, you could consider a combo and maybe buy an extra cab to stick on the other side of the stage. Spares wise, a set of strings, cables, spare strap, spare kettle lead for your amp, fuses, screwdriver, small torch, string changing stuff, tuner. I use two of those aluminium tool boxes-one for f/x and their associated mains units plus string wipes, patch leads, capo, slide and the other for P/A cables and an f/x unit that we use for the P/A.