Easiest way to clean an Apex: take it off the barrel and toss it in the trash.
Just IMO, though it is
For your chronograph question, you really have two options as far as a budget chrono goes. You can get an X-Radar (white) or the Paintball Radar (yellow). Not too much different between them, they both tell you the speed of your marker, which you NEED TO DO EVERY TIME YOU PLAY (sorry, but someone has to say it and be the *******). ActionVillage is great, but they don't always have them in stock. I'll do a little perusing and see if I can find a good store with them in stock and at a decent price for ya.