Modify PHP in wordpress.org Book Your Travel theme by Themeenergy

I built a Booking System site with this theme that i bought. [login to view URL] We need to modify the PHP to add some capabilities to the Accomodation and Vacancies items and search in homepage. 1-The BYT search engine for now only filters some of the input fields (Accomodation details) like Where (location), When (dates in and out), and some other we don't need. We need to filter by number of people too. That is; Where, When, How many people. 2-We would need to add "Minimum days stay" in add Vacancies (by season) form instead of add Accomodation form. Because OUR Accomodations have different "Min. day stay" depending on Season. In the theme its set in Accomodation, so the turnaround i have implemented is not working well. I duplicate Accomodations with different "Min. Day stay" and relate Seasonal Vacancies (dates and price per day). When performing search depending on dates input one may see duplicated Accomodations.... Booking is made impossible in certain situations beeing different Accomodations depending on the Season. 3- Synch the BYT reservations with iCal or Google calendar. But BYT doesn't support APIs.... so i imagine is not possible. And sure expensive.