Reply to Advice about cdj's

Hello, I'm a keyboard player and I want to incorporate scratching into live shows I do with bands.
I'm not intersted about the other aspects of djing, just scratching. a few questions:

1) what do I have to look for in a cdj? whould every cdj be suitable for me? any recommendations?
2) I noticed that when djs scratch they have one hand on the cdj (or vinyl) and the other on a fader that from what I understand
controls the volume. would I have to have a mixer? doesn't the cdj have a volume control?

Thank you for your help, I'm new to this and can use all the help I can get.