Network Switch to Handle Multi-Wan?

Would like to wire a residential high rise such that residents could split internet bill.

What would be the ideal design for such network:
1. Allow each unit to choose to be provider or consumer through the shared network, thus the case that two units wants to offer sevices of different providers with different last mile medium i.e. cable vs dsl vs fibre
2. Allow each unit how to connect to the shared network i.e. wifi vs ethernet
3. Minimize config change (both in-unit and outside of unit) per provider and consumer change
4. Provide fair dealing policies in terms of available network performance and fully utilize the max performance of each mult-wan links; ability to cut off a WAN when usage cap is reached.
5. Preserve identify such that ISP cannot detect the high number of connected devices or usage and attacks on vulnerabilities.
6. Allow future expansion possibilities to support smart condo and occupant sensing technologies available requiring digital networks.

this looks an awful lot like homework

So you're essentially looking to do link aggregation of unspecified numbers of tenants' internet connections on an ad-hoc basis with connection sharing...

Yeah. This is against most ISPs terms of service on consumer connections (it's essentially reselling). You can get your tenant and management company sued for this sort of thing.

Also, there's no real incentive for individual users with connections to offer up their connections and be providers.

This is just stupid... This isn't a power grid where you just "give" power back to the grid.

It's a lot of mickey-mouse config for no real benefit.

Pretty much what the others have said. In addition to this being an administrative nightmare given your requirements. I hesitate to respond with any more information because if this isn't homework, I feel sorry for your situation.

Who would be supporting that cluster-fuck of a mess?

All I see is this.

The word you are looking for is router. Just by reading the post, this is WAY out of your league.... I also hope this isn't homework from a school that teaches anything to do with computers if your title is how the question was worded...

I think you need a fairly cheap UTM device, free or proprietary.
DHCP to provide a 'guest' IP, Captive portal to choose the WAN link or network, route rules, NAT, port forwarding rules, all in one device.

Who in there right mind would want to run/manage that cluster F!!

Sounds like a setup that's more complicated than it has to be. Keep everything local unified as one normal network. Then at the router just have some kind of fail over or round robin or something. I'm not familiar with those kinds of setups so not sure on specifics but I imagine something like pfsense can do it.You have two wans, and each time there is an outgoing connection it just picks one for that session. That, or one is a fail over and is only used if the primary fails. You can't really aggregate two ISPs so the bandwidth is combined though, which is what I think you're trying to do?

Also if this is for an apartment, don't get a capped connection, make sure you get one that offers unlimited, even if it means lower speeds. Lower speeds is better than a $100,000 bill because someone decided to run torrents all night.

I conceptualize it like this:
A switch for every apt to distribute throughout the apt' drops.
Single feed off that switch, to a centralized location in the complex
separate network for each ISP, connecting the feed to each apt to the correct ISP.

Seems like a ton of hardware and headache.