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It depends on your windows and what you're growing and where you are. I live in Massachusetts. I have a large bay window that faces south, a bedroom window that faces south and a couple of windows that face east that get a lot of morning sunlight. I didn't use lights. After last winter, a few of my plants, despite very little water, could've used lights, so this year, I'll either give those plants away or rig some lights for them. IMHO, it's a learning process...constant adjusting and understanding your plants and what they need. That's part of the fun...deciphering the clues your plant gives you and adjusting what you're doing to its needs.

That looks quite good. If there are any damaged roots, you can snip them off. You can leave plant without soil for a bit, hopefully you can get better mix. If you have only this succulent, you could improve your cactus soil by adding perlite (very easy and inexpensive). It would be good if you sift it (cheep kitchen sieve from a dollar store would do :) to get rid of dust. Mix sifted perlite 50/50 with the cactus soil. If you could get hold of grit, it would be even better, mixing grit+perlite in approx. equal amount and adding about 20% of soil (I wouldn't do any more soil, you could do even little less. Your mix will be approx. 40(grit)-40(perlite)-20(soil)%). The grit should be about size of large perlite granules (about aquarium gravel size). The yellowish low end of your cacti (if not soft) could be either from being originally deeper in the soil (so not receiving light) or it could be (?) beginning of corking - that is a natural process with older plants. It is usually brownish and looks little like dry skin). Plant cactus into the mix. It may need some support to begin with, you could use layer of grit or even better, few larger rocks. It should go into best light you can supply. If the source of light is from one point, make sure you rotate pot approx. 1/4 turn every 10days-2 weeks or so. You could use piece of mosquito screening (from old window screens) or coffee filter to prevent washing out thru drainage hole. For future watering, you could use a bamboo skewer. Insert it deep into soil (1/2 way or more), avoiding root ball. If it comes out damp-cold feeling and/or with small particles sticking to it, there is still plenty of moisture and wait few more days to water. With grittier mix, water should drain out freely. Dump any excess from the saucer.

Echinocactus grusonii v. albispinus is probably the most likely. It normally has much denser spines than this, however.Notocactus warasii can get very woolly when large, but it usually has thin, hair-like spines. Hopefully yours will bloom soon. That always helps with ID.