Customize calendar

I have an extension called Breezing Forms that is using joomla's calendar. I want to customize it to... 1) Only allow dates to be selected that fall within a time frame. The time frame is 2 days from current date up to 30 days from current date. ALL other dates would be unselectable. 2) If 3 (I will need to know how to adjust this number also) records have already been created with the same date, that date will no longer be selectable either. A query would need to be created and run on form load each time since records can and will be edited. 3) I (The site Admin) will need to know how to make any date unselectable in order to block vacation days, sick days, holidays etc. 4) I (The site Admin) will need to know how to make any DAY unselectable. As in, make ALL Sundays or ALL Saturdays etc. unselectable. I assume (maybe I shouldn't assume) that this would be something that has been done many times and you will have done a similar project before.