I agree it's not likely the spindle was damaged by the crank but if you want to change the bottom bracket, you might as well go with a sealed cartridge unit. Shimano still makes a fair variety of square taper cartridges and they are quite reasonable in cost. Here is Loose Screws' web page for Shimano bb's in 107 up to 127.5 mm spindle lengths and they are only $22.
http://www.thethirdhand.com/index.cg...d=854944332127
Since you ..."don't know where to start..." and have none of the tools, I think this is a job for the LBS.