I've been reading through the documentation and see that you can have unlimited subdomains. My question is can I have a development environment set up on a completely different domain? My client has purchased SF and it (production) will be running on www.myclientssite.com. However, they have hired me to do some development on the site and I would like to set up a development instance here at myclient.mydevshop.com. Is this possible?
It is possible for development. If domain is different, that written in licence file, sitefinity will just show "Trial message" every certain number request. Usually it is fine for development process.