As long as the the host profiles requires any input it will not apply and ESXi will stay in maintenance mode.
Here is what you need: http://blogs.vmware.com/vsphere/2011/09/sample-scripts-for-automating-auto-deploy.html. I have use the ad-update.ps1 script to pre populate the host profiles answer file and it really works.
MAC addresses will be auto-generated if not specified.
Great, I'll check that script out. Thanks for the link.