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Routing question

I am allocated a couple of public IPs to use, but I also have to set up
my own router.  I have always been used to using private IPs and using
NAT to deal with everything.  I have a couple of questions:

The router will have two ethernet cards, just like when I am NATing,
right?  The router gets its IP for one of its ethernet cards for the
uplink side via PPPoE, which is a static IP.  What do I put for its
other ethernet card as its IP?  In the good old days, I would put
something like,, but now I'm lost.  Now that I think about
it, I suspect that I probably have to set the "internal" interface as
one of my allocated IPs, right?  i.e. if I'm allocated,
with the gateway being, the "external" interface will have
43.21, and the "internal" interface will have, say, 56.01?

Do I need to recompile the kernel with OPTION GATEWAY?

Do I need to set the sysctl ip.forwarding=1?

Do I need to run routed?  I will only be connecting one end to my DSL
modem, the uplink, and the other end to a hub, which will service all
the other machines.  Since there are only two interfaces, this makes me
wonder if routed is needed.  Most documentation talks about needing
routed for when there are multiple interfaces on the router.

I seriously doubt this, but do I need to run a bridge?  Seeing as how
I'm using PPPoE, I don't think that this is possible (unless my
understanding of bridging is flawed, because I think that bridging
requires that two interfaces have no IPs.)

Anyway, sorry for all the questions, but I have been looking around for
information concerning routers and all that for a long time, but all I
see are pages and pages of information about NAT.  Any pointers to the
right direction appreciated.