Custom DNS : not for first plan ?

On http://www.dreamhost.com/shared/comparison.html
i see
Custom DNS : NO
only on first plan.

What's difference with the YES on other plans ?

I have a few domains i wish to host in dream (well... in real too :) ), with sometime subdomains.

PS : can i host wildcards with dreamhost ?
like any.sub.things.peoples.can.type.mydomain.com

PPS : i don't need any domain inclued with my hosting plan right now, can i setup a plan now a choose my free domain later ? Or ask a little discount (even just 6$, because i really don't need/want a domain at dreamhost).

Thanks

You can use up your free domain later.

Thanks.

But i still think it should not be inclued because every one don't need it, and it's costly, not like giving more 100 GB bandwidth (because every one will not use it, that's why shared plan exist).

Custom DNS : not for first plan ?