Beginner Dj, Hardware/CDJ questions

You don’t NEED to know how to use CDJs at the majority of clubs but it is definitely beneficial. There’s only a handful of places that might be strictly use of house equipment only. There might be issues with space for your controller at some venues though. Generally taking your controller and laptop shouldn’t be a hassle. Arrive before it opens to scope out what the setup is like.
Using CDJs is quite straight forward so if you can find your way around your midi controller and software you should be able to work them out quite easily. Using the clubs mixer would be more of a challenge but again nothing too crazy.

99.9% of the time I have no problems setting up my controller and laptop and many clubs even welcome it.
As the others said, just practice beatmatching on your controller and you will be fine in the occasion that you need to use the CDJs. Always have a USB drive with your music as backup to put it into the CDJs.
Most clubs will have CDJ 1000 or 2000s and you should be fine with those if you learned how to beatmatch. Just do not panic and not get intimidated by the setup.
If you use VDJ just burn some timecode CDs most of the time the clubs will have the necessary gear (or CDJ 2000) that you can plug into your laptop and use the same as your midi controller and use VDJ to DJ. Just head to the VDJ forums and wiki and know how to hook it up.