Hunt Groups Scenario

Using Cisco CME 8.6.1 on 2901 router.

The business requirement I'm struggling with are:

1. That I use '2' as the hunt group pilot for our service desk as announced by our
    autoattendent. That has to stay if possible.

2. That '2' first rings my dedicated helpdesk technicians, and if no    
    one answers the second hunt group rings everyone in the office minus the managers

3. I need a third hunt group for sales which is '1' also announced by the autoattendent.

4. People calling in call leave a voicemail and then return to the autoattendent either
    during the mailbox greeting or after finishing recording their message by pressing '0'

5. Configuring a 7937G conference phone. I configured it as another ephone-dn but it just
    doesn't work. No dial-tone, no anything. I have no idea on this one.

As far as the hunt groups, I can get them to do what I want pretty much, but if I press '2' from my desk phone to place an outside call, before I get to the second digit the hunt group rings. '1' does the same thing. Not sure how to make this work.

How can I set '0' to get people leaving voicemails back to the autoattendent?

We're porting phone numbers tomorrow and I don't have these past pieces set yet, so any insight would be very very much appreciated!

Thanks for your time and thoughts.

Phil