[240 2NR]

Correct, you do not NEED to change brake fluid when you change pads, but it's probably a good idea as the fluid is probably crap, old, wet, and dirty (chances are it may even be original to '91). This means that the fluid will now be the weak point in your system. Just getting a sporty pad to operating temp could be very close to the boiling point of the old fluid.

Changing fluid is EASY (it's just a PIA). First get a good Dot 3 or 4 fluid (DOT 5 is not desirable, and I'm not sure DOT 5.1 is worth it, though I don't know enough about it to comment). So far the ones I have used or had recomended were Valvoline Synpower, Castrol GTLMA, and ATE Super Blue (gold same stuff, different color). ATE super blue is in my car now since it gets raced. Really high wet and dry boling points. If you plan to change fluid once and forget about it, you should probably stick to GTLMA (LMA = low moisture activity) or Synpower (avoid all race fluids as they are meant to be changed often and will absorb moisture quickly and will likely have low wet boiling points as well, depsite there high dry boiling point).

Either get some speed bleeders from Don at PDM-racing (if you go to the track or won't have help, get these as they allow you to change fluid quickly and solo $22 for all four corners) or recruit your friend to help you. Get some clear rubber tubing (1/4" IIRC, though I think the OEM and speed bleeder nipple are differing sizes) from Menards or other hardware store (6ft=$1, its cheap).

Then bleed brakes in this order for non ABS:
DR -> PR -> DF -> PF

To bleed brakes loosen bleeder screw (or replace with speed bleeder) and place enough hose over the nipple to run down to a catch can. About a half turn should open the valve and when you depress the brake pedal it should go to the floor and pump out fluid. If using speed bleeders continue to pump evenly until done and retighten, otherwise when the pedal is at or near the bottom of it's travel you must manually tighten the bleeder, then release the brake, open the bleeder, pump, tighen, release, repeat.

Things to note:
-Keep an eye on the resevoir level. Refill at the low mark. If it gets too low and draws in air you must start again.
-The hose has two purposes, the first (1) is to keep an eye on the fluid so you can see when the color changes from brown to the color of the new fluid (usually clear) and so you can see if any air bubbles are coming out (the fitment of the hose must be snug on the nipple so air is only coming from the bleeder and not outside). The other (2) purpose is to keep the fluid from dripping down on the caliper.
-Avoid spilling brake fluid as it is very abrasive and will destroy paint (and makes your fingers feel funny).
-Brake Kleen (I recomend the green can) is a good way to clean up the brakes when done.