So look for guidance on designing resorts and apartment complexes or condominiums. Private developers would have a better graspe of what is useful to people than urban planners. Urban planners get to impose their vision, private developers have to sell their vision.
Critical infrastructure is that which, if unavailable or affected negatively, puts people at risk of harm. Everything else may be useful but it’s not critical. The utilities you propose are probably CI. But even that can be highly distributed. Water catchment for example. Most likely is specific to each structure, since even if interconnected, they won’t actually share a contiguous roof. Same with solar power. Telecommunications probably benefit from aggregation and reselling access to the service, but this is most like private industry.
For minimum useful infrastructure for profitable occupation and economic growth, some things in your list would be consolidated. Frontiers don’t have “convenience stores”, they have “necessity stores”. People may buy luxuries there as a special thing, but the main purpose of such a store is to provide things that cannot be manufactured locally (either practically or economically).
So if you’re planning to provide space for such functions rather than expecting each seasteader to build their own, you’d want a general store that includes hardware, durable goods, groceries, etc and probably separately, a marketplace/market space for local exchange among local vendors and manufacturers (town square/commons/fish market/farmer’s market/flea market/swap meet space.)
Personally, I would expect that running a general store is a seasteader occupation. If I intended to do that, I would design my seastead to support that and provide my own space that could simply be adjacent to my market demographic (tie up to other seasteads). It could still be run as a Co-Op.
Meeting space- not sure if you mean like a convention center, or a conference room, or a town hall. Or even the fishmarket concept above. Frontiers typically have multi-purpose spaces for stuff like this rather than dedicated. The Inn might have a common room, the church is a meeting space, the school auditorium, non-profit orgs like grange halls and fraternal organizations have space. Weddings are often performed in all of these kinds of places.
Harbor/dock space is a necessity, and one of the first pieces that probably requires coordination amongst the population rather than simply benefiting from it. Individual seasteads could and probably would have their own docks for tying up a boat, but a larger harbor/marina requires coordination to use fruitfully and safely.
Transportation is a service. Without certain types of transportation (roadways for wheeled vehicles or fixed rail) there is not much need for transportation infrastructure other than a harbor/marina, and perhaps some radar tracking and beacon services (the latter of which can easily be provided by subscription or service fee by private enterprise.)
Personal services: medical, barber, salon/spa, massage, prostitution, tattooing, tailoring… space/shelter for any of these are best provided by the entity providing the service, just like any business owner.
Restaurants, entertainment and hotels- provide their own space. Possibly in the same structures. Banks/money exchange/financial & tax services/accountants the same.
One seastead occupation may be simply leasing space to these other business ventures. Strip malls and shopping centers choose to accept customers based upon optimizing the mix of complementary businesses quite often.
Schools are another topic that is often contentious. A well-educated population is fairly necessary to a free society. But publicly-funded schools are not the only, or often the best means of achieving broad-spread education. They are simply a means of gaining cost savings and streamlining convenience, not necessarily giving the best product. Increasingly, large physical schools are not necessary with the advent of modern communications and collaboration technology.