From my understanding, Varicocele is improper veinous drainage in the testicular region. I couldn't remember all the details so I had to do some research again. If you don't require surgery (for pain or shrinkage) then it would seem that the testicle health routine would be a good thing as it promotes blood flow and this condition tends to "pool" the blood in the area where the veins have dilated (opened up).
As with all things, talk to your doc and be slow and cautious. You don't have to say, "Hey I'm trying to add some size to my penis can I do these things..." Just ask him if massaging the testicular area to promote blood flow is alright.
As far as Penis Enlargement goes, if you have sex/orgasms without problems then I don't see how this would be much different. More intense but you should feel discomfort if there's a problem. Listen to your body and I really don't see why you can't benefit from it.