Tide pool organisms might actually need the battering of waves. If nothing else, you're definitely going to want very strong alternating flow.
Tank - bigger is better. Get the biggest tank you can afford.
Cooler - never used one. Sorry.
Filter - I like the Berlin method personally. Lots of rock and sand. Protein skimmers are a must. Waves on the shore are nature's protein skimmer, so shoreline critters might tolerate dirtier water than reef, but better safe than sorry.
"How do I keep the fish alive" can you be a little more specific? Do you mean alive on the trip from beach to home? 5 gallon bucket with a tight lid and a careful driver. If it's a long drive, maybe a battery operate air pump.
Someone stop me! Please! But... not just yet...
55 Gal Tropical FW
55 Gal Mixed Reef