Try looking up the sticky thread that says e36 parts and maintenance cost (or something like that). I don't know off the top of my head.
If you just wanna fix your steering slop I think front should do it. Will require an alignment after changing tie-rods I believe. Sway bars need not be changed, just the end links that connect the sway bars to the struts (if the links are worn out). Also while you're at it you might wanna consider changing dampers if those haven't been replaced. Just because changing it later on will require an alignment as well. Once again, I don't know how much an alignment costs here, but in the US (where I had my car) its like 90 per pop to be done by a reputable shop.
These cars are old and unless maintenance have been up to date, there are many many things that you need to address. But different people have different budgets and requirements. So whether you wanna do front and rear or just front to fix your steering slop is up to you. Rear bushings contribute more to the car's handling and tire wear and what not, and is harder to get to (RTAB, ball joints, subframe yada yada), and for the daily driver, generally more negligible.