Installation of the system is not difficult.
The bike itself is probably the most difficult but once you have done it, its not so tough.
Firstly, make sure the bike you get has a 68mm
bottom bracket shell width
, after removing the cranks measure the length of bb spindle, it needs to be at least 119mm but no more than 122.5mm. ( I think replacement cartridges go from 118 to 122.5 ) I have found 122.5
is just right.
You will need to purchase, crank removing tool, BB nut removing tool, each about $20, 15mm spanner for pedal removal or pedal spanner.
BB cartridges are under$20.
Two points to keep in mind, The right hand BB nut and the left hand pedal nut have LH threads (clockwise to loosen).
Some good bike info here, http://bicycletutor.com/cartridge-bottom-bracket/
Suggest you take your time and if possible practice pedal/crank/BB removal on an older bike.