One additional question. Is there a bus that goes from Collioure to Ceret? If so, how long of a trip
is it? Ceret looks like a very interesting town to visit in addition to Collioure. Thank you once again!
Rome2Rio.com is a good first stop when working on transportation issues like this. If it says you need to take a bus, you can often drill down and find a link to the bus company. If not, at least you know that you need to Google "Bus from X to Y".
It appears that you must first go north to Perpignan (by bus or train--train probably faster if the schedule works for you), then take a bus back down to Ceret. I've linked to the winter schedule. Perhaps there will be more departures after March 19, but it doesn't look bad at all unless you have to travel on a Sunday.
The easiest way to get from Collioure to Céret is indeed by bus. The buss from Collioure to Argeles Sur Mer and the a connecting bus from Argeles to Ceret. It will take about 1h20 minutes, but all the buses have A/C and all journeys are just €1 and there shouldn't be much of a wait between connections.
Here is a link to the timetables;
http://bus1euro.cd66.fr/horaires-et-itineraires-bus-a-1-euro/