Family Small Business Network Overhaul Advice

Background information: I'm a 21-year old student with Good computer knowledge and limited networking knowledge (revamped my home network). I understand the basic principles of networking but was looking for some sort of sanity check or advice on the plans that I have been setting up over the past week. I've been asked my by family to have a look at their networking and get it into shape, it's currently a dismal mess. They've had a quote of £590 to do some rudimentary rewiring, installation of a networking switch and of a new router from a local firm but I thought that was quite expensive. Currently they have the ISP-provided modem-router-ap connected to an 8 port gigabit networking switch. They have a couple of NASs connected to the switch which handle some database backups as well as some cctv recording. Most of the other ports are connected to a patch panel which runs up from the basement (where the networking is located) to the other 3 floors of the property. The patch panel is installed correctly with 24 cat5e cables which feed up to outlets so that is not of a concern. The wiring in the networking cabinet is a complete mess with only the patch panel installed correctly and the rest of the components on a box next to the cabinet with a mess of wires connecting them.

Requirements

• Organisation and wiring of the cabinet - inc. installation of new gigabit switch
• Gigabit LAN throughout - currently only 6 of the 16 ports on the office floors are useable; the quick fix has been daisychaining network switches at the workstations
• 4-fixed workstations connected
• New router - ISP provided speeds are currently 18Mbps down and 1Mbps up; upgrading to fibre soon so this will likely double soon - the issue is that the router is not sufficient for the number of users and is easily getting saturated when the users are mostly browsing the web.
• Wifi-covering the entire property with work, guest, and employee personal use. Usually 4 employees on the property with a usual 10 devices connected the the internet at any one time.
• Future Plans: Server upgrade; POE cctv; expansion for more employees; UPS installation;

Proposed Equipment/Changes

• ISP-provided modem in Bridge mode
• Ubiquiti EdgeRouter X 5-port Router - small-business class performance for a fair cost, including gigabit ethernet
• Netgear Prosafe GS724TP 24-port POE gigabit switch - Can be found locally for £100 (refurbished); POE for future plans; sufficient for patch panel and all outlets; future workstation expansion
• Ubiquiti UAP Lite WAP x2 - Researched Unifi and it seems to cover all our needs; POE powered for convenience/wire-management (close to outlets); do these plug into the POE switch or should i get a POE router and plug directly into that?; current setup not providing sufficient coverage so 2nd and 3rd floors w/o wifi, temp secondary WAP installed to cover area.
• Maybe (cost-dependent) Cyberpower 600VA/360W UPS - Currently there is a small 8-way power outlet with built in battery? - not sure about quality, capacity, and reliability.

Proposed Network Topology Diagram

Questions

• The ISP bandwith is 17Mbps down and 1Mbps up yet the internet is patchy and sometimes takes a long time to load when in use by multiple people - this seems to be an issue with the routing and not with the saturation of the bandwith as most are just browsing the internet, does this seem correct? If so, much of this should be solved when we install the edgerouter, correct? Anyway, I am looking into upgrading to fibre anyway as our ISP has quoted us a cheaper monthly bill for an upgraded service but that won't be installed for a couple of weeks.
• When I will be rewiring the cabinet I will be making my own ethernet cables and cable managing it all; this is my first time taking on a project of this size so are there any tips that you would recommend?
• I've never configured this router and these WAPs before, looking online the initial setup wizard seems to cover all of the bases and it's mostly specific requirements which require manual delving into the settings beyond this. Is this correct or is there any specific guides I should checkout beyond the manufacturers?
• I have the WAPs connected to the POE switch, is this best practice or should I be looking at a POE router and wiring them directly?
• I'm estimating that it will take me the best part of the day to get it fully configured and up and running, does that seem reasonable?
• Have I selected appropriate hardware for the intended use? Is there anything that would improve performance or where I can pick a more budget-friendly option?
• I know this isn't the place but have I provided myself with sufficient breathing space to allow extra expansion to an improved server and some POE cameras or is there anything I could do to allow this?

(btw, this is laid out in a similar post to mine with different requirements Link) Edit: Formatting