Read iptables.org documents, they tell everything you need to know. Probably the important factor is which iptables/netfilter versions you are using; if they're more or less the same (i.e. you're using iptables on each machine and not the old ipchains somewhere). Basically I think the commands haven't changed much, except from ipchains -> iptables. So yes, you should be all right. Also read
The filename isn't important. The important thing is that iptables can read the file's contents and understand the commands. After you've read the file (and therefore applied the rules), check
and see if everything looks good.