This is another vote for the RRS focus slide.
Also helpful is a geared tripod head, and maybe a tripod with a geared column - you don't want to extend the column much, but just having the geared movement over an inch or two is very helpful.
For backdrops and lighting you can do an awful lot by improvisation, which is what I do a lot of the time. A laboratory jack (a small platform that can be adjusted in height by turning a threaded rod) is a useful thing for supporting the subject.
I use daylight, flash, or tungsten at different times for lighting. Tungsten is easiest to control and to learn with, and you can pick up cheap used tungsten lights easily: you don't need really powerful lights, say 300W, and something like a used set of Lee Mini-Pro lights would be a good place to start. (Use the safety screens with them or, better yet, get a set of glass dichroic filters.) Small pieces of card or foamcore will serve as reflectors, painted black, white or silver, or with crumpled aluminium foil glued to them.
Have a look at the Novoflex magic studio setup as well. This is like a very small infinity curve and can be quite versatile, giving you more flexibility than a tent or cube.
Modelling clay, gaffer tape, cinefoil, bulldog clips, flower arrangers' wire, wooden dowel, etc., etc. will soon all be finding new uses in your house...