that will get you up and running. Changing the nameservers will leave wordpress as your Registrar. If you wish to make dreamhost after the 60 days is up, then you can proceed with the actual transfer.
Go to manage domains and click the "add new domain or sub-domain" and add the domain.
"Registrar" (or registration) and "hosting" functions are separate and independent of each other.
If you later transfer the registration, then when you renew the domain at expiration you will renew at dreamhost. If on the other hand you leave the registration at wordpress then you will renew the domain at wordpress.
The thing not to do is to let the domain expire at worpress, and attempt to pick it back up at dreamhost... that won't work, and you probably won't get the domain back.