Hi there! I am a 32A and I started NB approx. 1.5-2 months ago. It really depends on the structure of your body, not just your bust size... because I am so tall, I have a bit of a wider frame and thus more room for larger domes. I was originally going to buy smalls, but after posting a topic on the forum about it, found out mediums would probably be better suited for me. I'm so glad I bought the Mediums! I'm already almost completely filling them, and thus purchased the larges (with soft cup rings! I would def recommend this because it can definitely get painful without them). I just got them about a week ago, and have been actually been able to use those fairly well... although it does take a little extra effort to get them on. What I do, and what many girls do on this forum, is start out with the M domes for a little while, then change over to the L domes. This helps you get better suction because you already have existing swelling.
As for herbs, supplaments... I was taking PM capsules for about a month, but have recently stopped because it was causing some cellulite. I don't plan to use them until I feel I've hit a plateau and need a boost. My suggestion is to see what NB does on its own, then add supplements if necessary.
For lotion, make sure you use a lotion that is good for stretch marks, as you will likely develop them on your breasts if you don't. I just use a simple cocoa butter lotion, and I sometimes add a bit of Bio-Oil as well (which is also good for stretch marks - you can get it at any drugstore). But, as long as your using some type of lotion/oil good for stretchmarks, you should be good! Some people respond to lotion for better suction, and some to oil... it really depends. I personally find it doesn't make much of a difference for me.
Hope that helps!
Kris