Emails – I give it for free. This is a good selling point for me. Some hostings charge for email addresses, and in a few cases clients migrated to me just because of unlimited email addresses.
I do give access to cPanels, no limits on database or transfer. I have about 20 clients hosting on my machine so I monitor the hosting use and when one of the sites is abusing the resources, I contact the client to discuss. However, for sites which would abuse the data transfer or space (large ecommerce mainly) I always suggest the client to have their own dedicated VPS (~$50 per month). That being said – I try to host only very small sites.
You should have an affiliate account with your favorite hosting (I like wiredtree and MT, for more demanding sites I like Rackspace and AWS), so you can earn referral fees.
For backups, I use whatever plesk or cpanel provides (with backing it up on an external AWS webspace). I use codeguard.com for more demanding clients.