Customizations for an existing Word Press Module (edited)

PLEASE READ EVERYTHING BEFORE PROPOSING YOUR HELP... We are interested in buying a Wordpress module called "Booking Calendar Contact Form". You can find it at the following address: [login to view URL] But we'd need some customizations since this one fits only some of our needs and not all of them. This module is one of the many Booking Calendars you can find around. The one I’ve linked is a basic version but In its PRO version it allows to have multiple calendars. And it is useful because we have to manage different situations. For instance: The first one is the reservation for a Course that lasts few hours and ends in one day only. The second is the reservation for a Course that lasts five days, from monday to Friday, with no days off. These two cases are quite easy to be managed. The third is a little more tricky instead. We need to take reservations for only one fixed day per week, for a period of three (or more) weeks. I mean: this Course is divided into three (or more) lessons with a frequency of one lesson per week (eg: every monday). So it is necessary for us to have this feature: when an user select one Monday (or any other fixed day) the following two Mondays must be considered “booked” as well. (please note that instead of 3 they could be 2 or 4... so it should be a customizable value. But we can discuss it later) If you take the time to try their demo, You'll see that you can select the "Start Reservation Date". And you will also see that it is possible to select the "Enable Fixed Reservation Length" option. So, if you set only Monday as "Start Reservation Date" and give to "Fixed reservation length (days)" the value of 15, you will book all the three Mondays, of course. But in between there will be all the other days. And they will look as booked. With the help of some css it is possible to make some workarounds to show as reserved only the the "allowed" days (the "start reservation date") but in any rate the system will consider them as booked. And we would like to avoid this behavior. It should be done by adding some other option like "exclude non-start days from booking" or "consider as booked only the Start Days". You will understand all these things better by trying the demo... We also need to fix a max number of attendees for each course. The native “overlap” function works fine but we'd need to manage this thing with a fixed number. Last thing is the possibility of placing the calendar with the summary of the bookings into a more friendly admin page (actually it can be copied from an existing one which is full of settings and it is not so “friendly” for a non expert administrator). More infos will be given after the job will be assigned.