Re: how often to contact
Spontaneity is a big one. Another thing is to keep the conversations fresh. From knowing each other for a long time, the conversations may get and seem stale. As long as you keep that same spark that was at the beginning going, you shouldn't have any problems whatsoever. The best way to do this is to still try and pick her up with flirtatious moves and so on as if she wasn't yours yet.
Your disinterest bit is a good idea. So far, she is used to hearing from you every single day. Take a break for about a week and don't initiate any of the conversations. Try to get her to chase after you for a bit. If she doesn't hear from you for a day or two, then you can initiate the conversation. Keep the power of the interaction balanced between you two. Sometimes she will do something, and then the other times you will do something.
"There is no better than adversity. Every defeat, every heartbreak, every loss, contains its own seed, its own lesson on how to improve your performance the next time." - Malcolm X