Is it possible to export reservations to csv or other formats ?
Modern booking allows to export list of reservations to CSV format.
With excel or other software you can easily convert csv to xls, xml and other formats.
I don't want to use payments, can I disable them ?
Yes, reservations can be made without redirecting user to payment page.
Can you develop custom payment plugin ?
Can user cancel his own reservations?
Can I disable specific days ?
Modern booking allows you to disable days based on date and weekday.
For instance you can completely disable reservation for every Monday, Tuesday, etc. or dates like 2018-10-05, 2018-10-06, etc.}
Where I can change terms and services link ?
Terms and services link and text can be found in language files, please see main folder /language/en-GB/en-GB.com_universal_booking.ini