I am not sure about the proposed fee charged to place an order in the book, I imagine most people will just pay the fee one time and then change the existing order to avoid paying more fee's, for example you could place a sell for 100 MSC at 0.15 and after it is sold move your order to 1 MSC at 0.9 or something that won't be purchased, then next time you wish to place an order change it again.
So if you proceed with this you might as well just change everyone a 1 time fee to use the order book, still not sure if that's the best idea - it may just discourage people from using the order book at all for standard trades and they will just be posted in this thread instead.
Why don't we start with a maximum of three days before your order will be removed? In this way it will stay up to date and no fee have to be charged.
I agree that something like this is the best solution. But this is not really ideal, for example J.R has posted his sell order 1750 MSC @ 0.7, I'm sure the order is still valid after 3 days and I doubt he wants to keep posting it again. Which is why I proposed that all overlapping orders are removed after X days rather than every order.