Go to your .minecraft/mods folder and delete the mod you don't want to use. Only one you must keep is the CJB_MAIN.zip file. Also everyone that plays ECC and uses cjb must delete the CJB_QUICKCRAFT.zip or else they will not be able to craft anything in game at all.
You have to donate to be able to use the fly feature. ecocitycraft.com/donate Fly feature is $60 USD.
Does cjb make you be able to dig with the normal speed if you have eff4 or 5 like it doesnt slow the speed of digging the same?
It is the same speed as if you didn't have CJB. Plus with 1.4.2/4/5 you now have to use Forge to get it to work properly with Minecraft. I have heard of people not using Forge and getting it to work, but I don't want to spend the excessive amounts of time trying.