There is a convenience of being able to interchange all your disconnects on all your kegs, but thats all it is. It isn't a necessity as long as you have enough connectors for the kegs you have. The different shapes between ball lock and pin lock could affect configuration, but that is mostly dependant on the shape and size of your keezer. If they fit, you're good to go.
As for the regulators, no you don't. You can easily set it up with either a distributor bar with shut off valves or just a bunch of T connectors. I would caution you against the T without valves method, as it can be a real pain to find and fix leaks when you are unable to isolate sections of air line, but if you're really on a tight budget it can be done. Also, valves and multi-body regulators are easy upgrades later on if you decide you want to expand the flexibility of your system. There is a benefit to having precise control over each keg's pressure individually, but you can still serve good beer without it.