SEM, I don't think you're overestimating anyone's ability to learn. But you are missing a few key points here.
First, is that this network will not be designed, created and implemented as easy as you think. You, I and a few others may know a few key hardware that is needed to put such a network together and make it work, but Dan here is not in that atmosphere by his own admission. Not only does Dan have no inkling of the required hardware and it's relative performance, capabilities and limitations at this scale, but I'm also quite positive that even with that information, he would still be challenged to bring it together into a cohesive, stable and secure network
system. (Dan, please correct me if I'm wrong here. I'm not belittling your knowledge, just trying to read into your first post to help as best as I can).
Secondly, in any large organization (like the church here in question) that implements a technology like WiFi, even if just 50 people were using it initially, in a very short time period (less than a year) it will be closer to 50 people that do not use it at all. Planning for 30% to 50% of usage is very shortsighted in my estimation and experience.
Still, that doesn't mean we need to deliver a network today that can handle 650+ devices. What that means is that we design and build the network in such a way that the ability to handle more devices as needed is as straightforward as possible and at the lowest cost too.
Getting volunteers with Dan guiding them to run CAT5e cable (or higher), to appropriate locations throughput the premises, following a good network and WiFi design (from a professional) that takes the above points into account is the best use of volunteers here. Including Dan's own time and efforts.
Choosing which particular hardware to buy is also for a person with experience in not only the hardware, but also for taking into consideration all the details and requirements that the church will need now and forward. This is why this should be done with quotes from 'all' pro's working in his area. The true network pro's will quickly rise to the top, especially when contrasted and compared against the less than stellar ones (Dan will get some good knowledge just by acquiring these quotes in an organized and systematic manner).
Finally, with the design in place, the hardware chosen and the current level of service and quality determined (in addition to the future growth of the network as needed taken into account), Dan may then be at a place to implement the network with some additional learning and coaching from forums such as ours. I still think that the vendor who won the project should finish it though (the network performance should be tied to the notion that the job is 'complete and finished' and ready to be paid for).
One important aspect of volunteer type organizations is that any one individual is around for a relatively short time. Even if Dan acquired all the information he needed to design, implement and physically create the network by himself for the level the church requires today, that work will all be for nought (most likely) when he is no longer available to volunteer and the network requirements change for the church. Going with a professional, with a network design that is blueprinted and a company that will be around for (hopefully) decades, is the best way forward for most non-profits. Even if the initial costs are higher than a purely volunteer driven (hardware only costs) approach.
Some of my initial thoughts on this network are:
1) If the congregation did
all need WiFi access consecutively; that could be 10 to 20 AP's in a relatively small area.
2) If multiple large areas like the above are part of the church's design, another 10 to 20 AP's would be needed for each such area too (think Church, main hall, gymnasium, lower hall, etc.).
3) The above is 'in addition' to the AP's needed to adequately cover the rest of the 30,000 SqFt premises.
4) Guest WiFi access is more than likely needed and required everywhere on the premises.
5) Staff WiFi access is probably not needed as broadly, but it depends on how the church is run (details matter).
6) Running LAN cables and power lines as needed will be the most labor intensive part, especially if these cable runs are tested and verified. Final configuration and optimization of the network will be a close tie for the labor costs.
7) A secure (no windows), cool and central room to run all cables to is also needed (I never recommend this to be in the basement, for flooding reasons, unless all equipment (and AC power plugs) are at least 4 feet off the floor/ground).
8) With all network equipment (from the ISP's modem to the switches, routers, AP's and NAS' used), make sure you have a good quality UPS hooked up as needed for
all of them.
9) Get all quotes in writing. Including minimum network levels of performance guarantees.
10) Consider having at least one or two (or more) 'extra' units of each type (AP, switch and if critical (for the Staff network), even an extra router too) on hand that can be switched out for a failed unit quickly. You'll be surprised how fast models are no longer available and require a major change in the network (at a far higher cost than having a spare handy).
Dan, more than anything else, I would not recommend any hardware that requires an annual fee just to use. Nor would I recommend anything that was cloud based either.
Another option to avoid? The new 'mesh' network type hardware. It may work as advertised for a few nodes and a few users/devices. But, I think the performance will buckle under it's own weight (internal radio admin overhead) when the loads you are likely to see at your church reach a certain (low) level.