Car Ferry from Split to Stari Grad & from Sucuraj to Drevnik

Dear All,

Please help me cause I can’t find such info on the web page.

On 6th July I need to go via ferry from Split to Stari Grad ( by car ) and then on 9th go via ferry from Sucuraj to Drevnik ( by car ).
Do I need to book the tickets in advance via internet or can I buy them on the spot ?
If that is recommended is it possible to book them on the net in advance ?
As this is high season does the waiting queue is big ( in hours  ) ?

thanks in advance
peter