You are describing the “free state project” that Libertarians attempted to do to New Hampshire back almost 20 years ago now. If someone had enough money you could easily do this in extremely small populated counties out west. There are several entire counties in Montana with less than 1,000 in population. There’s one in Texas that’s around 100, the biggest key to this is doing it covertly through shell companies in little pieces at a time. Walt Disney famously did this when buying the land to create Disney World in Florida and was able to through his shell companies create the now infamous “Reedy Creek Improvement District” which was until several years ago a quasi-county level government agency wholly controlled by the Walt Disney Company. So it is feasible in principle.
To answer your questions
1 I would setup a government structure similar to the old New England towns which had the most participatory government structure with “town meeting” I would structure it a bit different though in that I would have the newly placed residents would petition the state for home rule powers (depending on the state this may be almost impossible to do and serious research on the selection of the state must taken into consideration otherwise the overall plan would fail because of certain state statutory obligations on non chartered counties, I know this very well having lived a chartered county in Florida because in 2018 a state constitutional amendment was created to clarify that all counties regardless of charter status must have a sheriff, property appraiser, tax collector, supervisor of elections and clerk of the court.) The biggest impact was the method of filling the position of Tax Collector before the amendment in Dade(aka Miami) and Volusia (where I lived) these positions were appointed by county commission not elected.
TL;DR research the state’s laws on how counties are treated and if home rule via a charter is allowed because to create one.
2 Keep the land in several different perpetual land trusts to keep the state gov happy and run it in the style of Singapore.
3 City creation depending on what state you are located in may be next to impossible (again Florida) or extremely easy (Missouri) depending on the types of services that may or may not be allowed based on state law you may not be cities.
4 This is extremely tricky but if we follow the shell company model and they are bona fide 501 (c)'s in the strictest sense of IRS code you should be able to get around most of the issues at a fed level, however if you stake your claim in areas where the feds own a ton of land via the BLM or a Native American tribe you may have an impossible task ahead of you. The state situation would be different again depending on placement and depending on locale you may get to have a state rep or senator in the legislature that would lobby for various tasks or clarify what the project is all about.
5 Never heard of California forever until now and I will say California is probably about the worst state in the country to try and make such a project work, it’s called Commiefornia for a reason, choosing what state to start your project in is the biggest decision you can make.
6 Depending on where you choose to do this project you may actually get a warm welcome as many people in rural areas would be happy to see more independence for their community but under current conditions they may not be able to do it.
7 Ideally walkable, if out in the west I would want to start small and make it like the old western towns that you saw in old John Wayne movies. But you had ways to get out of town that aren’t limited to horses and trains.
8 Under my land trust plan I would reserve only a small amount of land for government use which would for administration, courts, jail and other tasks of which the state obligates a county to do.
9 The design I have in mind would be to create a fully sustainable community with the protections of a county government/land trust in this scenario. Intentional communities would be welcomed with open arms as one as they adhere to the charters of the county and land trusts. Which would include having “do no harm, take no sh$t, no use of coercion or force” type policy.
10 I think I have made that case in all of the previous points, if not ask me to clarify lol
