You should only need 1 or possibly 2 remote mics and only if you struggle a lot in noise. It all depends on your lifestyle and brand of hearing aids. Roger mics cost about $1500 and other brands cost about $500. The Roger Select is probably best in noise and you could use it with other brands but would need a Roger MyLink neckloop to interface with a t-coil. Compatibility matters so ask audi and be sure you can return things after trying them. If you need to hear tv computer or phone you should use BT streaming.
Public venues (not houses of worship) with 50+ fixed seats are required to provide receivers and neckloops (they have a cable for the jack). You don’t need to buy any of that.