basic outline of exchange setup

hi guys,

installed my own sbs2003 box i got from a company that upgraded...lucky me.

i have everything installed AD etc
got the server sitting behind a netgear fvg3318 vpn firewall...all is working well and i have a laptop and a desktop joined to my domain.

im not using dhcp on the server as it wont be on all the time...i have configured dhcp on the firewall
my server is addresses 192.168.1.100 and my firewall is 192.168.1.1

i have set the servers DNS to itself and my clients DNS is like this

192.168.1.100
192.168.1.1

i installed exchange last night...wow!!! took a long time
and want to setup my email on it

i want to outline how i think it should work, what i guess and maybe you guys can be nice enough to clarify a few things for me.

ok so...i realise i need a static ext router address for my network...i dont have one..so i will get one

then do i point my mx records at my hosting company to the ip address of my router (external)

but on the exchange side...how do i configure / change the addresses of my users? my local domain is fds.local and all addresses are pointing there...but this isnt my true email addresses i want to connect to...so im in the dark on how exchange is configured to connect to these accounts...i dont want to use pop connector...i dont think thats how its done in most cases. i will open port 25 on my firewall to allow smtp traffic in.

lastly a friend of mine...who is no longer with me...setup user accounts like wayne brandon wayne.brandon and told me it was a good idea to do so...but when he explained i really didnt follow him

any info appreciated
pk