Using Comcast to provide and manage dns service for our own in-house web server(s)

We are considering upgrading our business  internet package (currently starter with one static IP and no other features.)

We want to:

a- use Comcast offer "custom domain name - free for one year through Comcast."

b- Add one email account, hosted by Comcast

Before we sign up, can someone confirm that Comcast can:

a- get our custom domain .... ourdomain.com,

b- set it up for the one email acct. we purchase as firstuser@ourdomain.com

c- provide DNS service for a server we host named server1.ourdomain.com and potentially a second server in the future called server2.ourdomain.com.

From looking at PTR update request messages in the forum.... if we can use Comcast DNS for our own servers, is it safe to assume that we users make PTR requests to Comcast and Comcast does the entries and changes?

Thanks in advance to anyone who can answer these questions.