Taken from the leaflet we got with our documents last time
" You are allowed to take ONE medium sized case per passenger (this includes kids), that should weigh no more than 20kg when full. Please do not bring large suitcases with yoou - the risk to you is that we may have to leave it behind. Your hand luggage can be stored in the overhead racks aboard the coach. Large pieces of luggage may need to be kept under your seat, or be placed in the hold of your vehicle, on request of your crew"
Can't help on the timings I'm afraid we're about 235 miles from Dover and the journey took us just under 6 hours with an hour stop, plus 2 x 15/20 minute pick up stops, so not too different to what I would estimate myself if I was driving.
In the same leaflet it states
"There will be one 45-minute break on each feeder journey, for the opportunity to stretch your legs and enjoy refreshments, if you are picked up within 3 hours of the port, you will receive a short break at the Interhcange. Refreshments may not always be availale on your feeder service, but they will be available on your tour coach."