1. Can I connect the Comcast modem after disabling the dhcp feature on it to the e0/1 port?
yes, you should be able to do this, the modem is just to covert the signals traveling from one medium into another, I'm not sure if the dhcp feature comes from the modem itself as it should come from your isp's dhcp server. now when assigning the ip address to e0/1 you need to figure out what ip address is needed to be assigned, I assume that whether is static or automatic you may still have to get it from comcast and assign it statically on your end. check with comcast to know what ip address is needed or is getting assigned and if a dhcp feature on your router is required to be enable or disable for this.
to route internet traffic I would suggest the following
if e0/1 is your default gateway, you just need to
1. assign the ip address from the isp provider the the default gateway interface
config# int e0/1 (enter) config-if # ip address [ip address] [sm ] <- get this from comcast config-if # no shut
2. create a default route so internet traffic goes out of e0/1
config# ip route 0.0.0.0 0.0.0.0 e0/1
3. depending on what routing protocol distribute default routes accordingly to other routers if needed.
Answers & Comments
1. Can I connect the Comcast modem after disabling the dhcp feature on it to the e0/1 port?
yes, you should be able to do this, the modem is just to covert the signals traveling from one medium into another, I'm not sure if the dhcp feature comes from the modem itself as it should come from your isp's dhcp server. now when assigning the ip address to e0/1 you need to figure out what ip address is needed to be assigned, I assume that whether is static or automatic you may still have to get it from comcast and assign it statically on your end. check with comcast to know what ip address is needed or is getting assigned and if a dhcp feature on your router is required to be enable or disable for this.
to route internet traffic I would suggest the following
if e0/1 is your default gateway, you just need to
1. assign the ip address from the isp provider the the default gateway interface
config# int e0/1 (enter)
config-if # ip address [ip address] [sm ] <- get this from comcast
config-if # no shut
2. create a default route so internet traffic goes out of e0/1
config# ip route 0.0.0.0 0.0.0.0 e0/1
3. depending on what routing protocol distribute default routes accordingly to other routers if needed.
I hope tha helps.