Hardware recommendations needed

Hello there,

I'm looking for a mini pc to make a custom internet router with
FreeBSD on it and I need hardware recommendations about what is better
to buy.

This mini pc must have and support with FreeBSD following things:

1. One SFP port compatible with 1.25 Gbps SFP fiber-optic transceivers.
2. One or more 1 Gbps Ethernet RJ45 port(s).
3. Ability to work (including BIOS setup) without a monitor and a
keyboard using only a serial terminal instead, i.e. using another
computer connected.
4. Two USB ports or at least one USB and single RS232 port, i.e. one
port to connect a bootable USB drive with FreeBSD installer and a
second port to connect an external serial terminal.
5. WiFi
6. Ability to work with the latest FreeBSD and to "make world"
(rebuild everything) in a reasonable time (not days).
7. Fanless.

Not sure about the CPU architecture. Could it be a 64-bit x86 or
better to think about something else?

Regarding the serial terminal connection. I didn't use it for a long
time. The RS232 port isn't available in today's computers. Is it
possible at all to make a USB to USB serial terminal connection, like
we did in the old days with two RS232 ports and a null modem cable?
I've found there are RS232 to USB adapters people use to connect a
terminal emulator on a laptop to an RS232 console on embedded devices.
Is it the only option today? In case it is, could you recommend one as
well?

Regards!