Can I use the MMM spawn rates options with fcom?
Should I just use the fcom spawn rates plugins?
Can I use safer roads with the spawn rate plugins?

Why start a separtate thread for an FCOM question? That's what this one is for http://www.gamesas.com/index.php?/topic/1215773-relz-fcom-convergence-and-ufcom/

MMM spawn rates will effect only Mart's creatures found in the mod, so it's always advised to to use FCOM plug-ins where one exists.
Safer roads wont effect spawn rates.

Somewhere in the MMM threas or FCOM thread it states not to use safer roads with one of the spawn rate plugins, so check into that. The rule of thumb IIRC is that if there is an FCOM plugin equivalent to MMM use the FCOM plugin. But best to ask in the FCOM thread.