having done parts of this myself, allow me to offer some suggestions.
you can certainly do *some* of the work but your effort combined with the volume/speed of completion will not match that of an experienced crew.
due to the Great Recession now underway there any many pool plastering crews desperate for work and they will gladly bid your pool. watch out for the common trap of being bid a very low price only to be jacked up on the back end in the middle of the job ..... "uh huh, we've found some major spots here, the price must be adjusted by xxxx.xx..".
in your case, depending on the amount of damage, you can safely estimate that 4 to 6 large trashbarrels full of old plaster need to be removed (each weigh about 300 lbs) to expose the gunite surface. you may have more in case the walls also have soft spots so the extra work in chipping away this old stuff will increase the labor/cost/debris removal and it will increase the amount of plaster/diamond brite needed to re-plaster the surface.
also be aware that the crews that compete for your job speak to one another. thus, it is common for one fellow to offer you the low bid, while he also works in the same crew that offered your the highest bid and if you accept any of the bids, pretty much the same faces show up to do the actual work as they all work for one another or with each other. handle yourself accordingly.
in the deep south a 15k to 18k pool with diamond brite costs normally 2k to 2.3k and you can have a better deal if you pay all cash. normally it takes just 3 days, one day to drain, 2nd day to chip and coat with bonding agent and 3rd day to apply multiple coats of plaster.
if you add other features, tile repairs, coping tiles for steps, etc. the price will go up a little.