Need help/suggestions for different Wifi networks for 4 or 5 different apartments

Looking for some basic pointers on hardware, setup and anything else needing consideration for the following scenario. We're starting from scratch, except the ISP provided router which we don't have much control over. This is quasi-commercial, so felt it best in this sub rather than /r/HomeNetworking ... hope you agree. [Realised I ought to X-post]

Setting: This is at a holiday complex where we own 5 apartments. We're not always there to do on-site admin, and we don't want to have someone from there 'on hand' to fix things.

Need to have: Remote admin control, so am hoping to set up a Raspberry Pi [or similar, discreet device] so I can remote into the router settings from abroad if and when needed. Some steerage on this would be great, not used Pi before. This would used to change Wifi passwords for each of the Wifi access points (ie different for guests etc) - would be good to know if someone is hammering the net and making it awful for other guests, for example, and then to be able to throttle or disable access. ^{If the net goes down entirely that's another matter, and not really what I'm worried about finding answers for here.}

Ideal Scenario: The aim is to have a single access point, ideally PoE to avoid having to find wall power always, in each of the apartments (model/brand suggestions please!). This will be based off ONE inbound internet connection in the most central apartment of them all.

Yes, I know it's going to go south in terms of bandwidth, however this is for email checking and Facebook for our guests, not torrents/streaming/etc. It's a ~70mb fiberoptic line. This is to save (a LOT of) money and to centralise control of the connections, ideally remote admin as mentioned.

The apartments are not one next to the other, nor would we want to share wifi networks between say two apartments, so we plan to run ethernet cables (from the router) to a sensible spot in each apartment, where we will have a Wifi beacon.

Maximum distance from router (ISP) to apartment is about 150ft, 120m, nothing more.

Any ideas welcome, I have about 1 month before I head out and would like to either buy the parts in the UK before flying out or at least know what I need to order (in Canaries).

Many many thanks in advance. If this would be better in another sub, let me know!