I’m not dreamhost staff, but in my experiences after 7 years using dreamhost, i can suggest you the answer would be:
1, They can help you to transfer from old to new, but you should do it yourself.
2, Dreamhost have 97 days money back (that mean over 3 months), and even if you do not happy in the middle of range (for example 3 years and after 1 year, you do not happy, you can ask theme to cancel)
3, Dreamhost do not control or related to your marketing process so, i guess no, they dont. But they guarantee the uptime is 100%. In 7 years i use, exactly it’s not 100% but they fix it fast, down time is not more than 30 minutes maximum. Downtime here mean server downtime.