ER-X-SFP should do fine.
If you need more processing power, then an ERL.
ER-5 only has three (3) switch ports.
ER-8 is overkill (unless you're planning on more than 1 physical LAN subnet, and even then, it's probably overkill).
With the exception of the ERX, ER-X-SFP, and ER-5, none of the ER line has onboard switching capabilites.
As for connecting the fiber directly in, that depends on how it's being provided. Some providers (such as AT&T in the US) require the use of their modem (as it's got their firmware on it).