1. Because it is crowded and full of interference from other devices.
2. User manager authentication, voucher authentication, RADIUS authentication
3. Disable concurrent user logins (also could set Maximum concurrent connections to 1).
4. The portal page.
5. Voucher authentication or RADIUS MAC authentication with the MAC authentication secret set.
6. RADIUS authentication.
7. DHCP service.
8. No; pfSense is the RADIUS client.