Modem vs router to replace leased modem?



New Member
I have a eMTA (for phone) which TWC won't let you own for some, no doubt stupid reason.
I don't feel like paying $8+ each month for use of their integrated modem even tough they don't charge extra for use of the eMTA which I would still have (more stupidity).

Four questions:
1. Pros & cons of a separate modem vs a router (other than if one or the other function of the router goes down you have a problem).
2. Input on a Netgear N450 router (on TWC approved list).
3. Whichever I go with, my other concern is dropping the modem portion lease on the eMTA until I establish a problem free replacement. Will TWC allow their 'modem' to remain active until I determined my replacement is ok??
4. Can modems or routers that have a USB port be used to host a HDD for network storage?

I'd rather not have three devices hanging on the wall (eMTA, modem & existing Linksys 54 router), but I'm concerned about reports of stability of a combo function router. (crashing, lockups etc.)