Pretty easy to do, but if you get it wrong, then the timing will be out, and could do some damage. Only attempt if you know how to install your own timing belt.
I wouldn't remove the VCT, it's one of the best bits about the RB25's.
To tune the cam gear, allow 1-2hrs of dyno time. With stock cams the benefits are small, more worthwhile if you have a set of aftermarket cams to tune.