hello Sebastian Kwiatkowski,
solution for issue 1
check the image Hasbinarycontent attibute is true or not you also can constrain your data by it.
if image still not visible you can access image by Url for that use deep link module
you can show image in mendix by Url also
solution for issue 2
add two attributes in Booking Entity (Start and End date [DateTime]).
add two input parameter of Datetime type in same MF in which you are Executing OQL.
Now When user select start date and end date on the page call the same MF on change – and pass the Start Date and End Date.
Now Update your MF
if StartDate and End Date !=empty then go to oql with WHERE Condition with Attribute Start and End Date
WHERE Booking StartDate >= $StartDateParamerter and EndDate <= $EndDateParamerter. so data will be filtered after selecting both date
go with your previous OQL which is fetching all data without filter.