Thanks for the business. Happy to hear you're enjoying Mastery!
One of the best ways to learn drinks is to go through a phase where you just order a new drink every time you go out. Grasshopper this night, White Russian the next night, Old Fashioned the night after.
Another great way is to buy a mixology book (or download an app - they have plenty of them for smart phones), buy some ingredients, and try out different mixed drinks when you have girls come over. Can also do a date where you have girls come to your place, you pick out a drink or two to make together, then go out and buy the ingredients. Then come back and mix the drinks.
You can also take a bartending class. Lots of fun, and gives you some good basic technique to work with.
For a few basic/popular drinks, Darius has an article here worth a read:
How to Mix a Drink to Make Her Taste Buds Pop
As for bringing / buying bottles. Bottles are a great way to get easy conversations with girls at nightclubs, but they're often expensive. I wouldn't worry about that unless you have money to throw around on them (or you've found some kind of bar where you can bring your own inexpensive bottle in and not be charged a lot for the privilege). But if you have one, just offering to pour drinks for girls who are passing by can be enough much of the time. Some will take the drink and keep moving, but many/most will stick around a while, and it's usually a pickup goldmine. That said, you will tend to run through cash like nobody's business doing this in most venues.
One final note: I only ever order one drink anymore at this point. Doesn't seem to hurt me any with girls though, probably since the focus is on what we are doing and not what we are drinking ;)