If the entire domain is going to be hosted at dreamhost, it's much better to simply change the names of the nameservers for the domain to
ns1.dreamhost.com, ns2.dreamhosr.com, ns3.dreamhost.com
Doing that allows dreamhost to manage all the messy individual entries automatically. I say messy because you mentioned the MX record as well. The extra entries required for SPF and DKIM do in fact get messy. Additionally if your nameservers are pointing elsewhere and dreamhost makes certain hardware changes during maintenance, an IP might change (it's rare, but it happens), if nameservers are set to dreamhost then that change would be handled automatically, however if you are manually managing records elsewhere as you are proposing then your stuff breaks until you figure out what happened and go make your manual edits.
Also with the method you propose, don't remove "full-hosting". If you do your stuff won't be served.