are there any instructions for how to mint zdrips? I'm guessing it's in the privacy tab, but I don't see exactly how to mint the coins.
Zerocoin is currently disabled via spork until circulating supply increases to a point where it makes sense to enable it - the zerocoin protocol doesn't work as well for coins with a low supply. We will provide instructions on minting zDRIP's well in advance of zDRIP activation.
Why doesn't it make sense to enable it right away? Doesn't every transaction on the network now leave a trail?
It leaves a trail yes - but the trail for a zDRIP transaction goes from a sender to a masternode. From there, it's sent to the recipient - but mixed among all the other zDRIP transactions (so there's no way of tracing directly from sender to receiver).
Part of how zDRIP works is you cannot send any amount - decimals aren't possible so there's no such thing as, for example, 1.5 zDRIP. Instead, you send denominations, similar to how you would give a shopkeeper a $10 note and a $5 note for a $14.50 purchase. You'd then receive the change back from the masternode. The reason for this is that specific amounts remove privacy. For example, if I were able to send you 12.4567873 zDRIP privately, it'd go to the masternode and then to you - and, whilst there is no direct link, one could see the 12.4567873 leaving your account and arriving at the other and could reasonably assume the two were linked.
In the above scenario, you'd send 15 zDRIP, 13 zDRIP or some other amount depending on what you hold and receive the appropriate change. Your zDRIP would be mixed with all the other zDRIP for that block before the sending to recipients would happen and this makes it impossible to make a link between sender and receiver.
The denominations (think of them as notes) possible with zDRIP start at 1 zDRIP and go up to 5000 zDRIP. However, where a coin supply is low, these denominations wouldn't work - think of the dollar as a currency where only $2,000,000 existed - what would be the point of a $5,000 note and, if it did exist, would you not hear about it's travels from time to time. We need a circulating supply where a single 5000 zDRIP denomination doesn't represent too large a proportion of the overall circulating supply. At that point, the spork can be updated so that zDRIP is activated.