I have been raw feeding for 6 months and it would take something disasterous to make me go back now as I had a pup who had the constant runs who can now eat anything without problems.
There are slight risks I'm sure, dogs who swallow rather than chew could choke on a bone but I have heard of dogs choking on kibble too so it is about calculated risk to me.
Bacteria wise, dogs are not human and are physically built with a much shorter digestive system than us, because they are designed for a raw diet. Wild dogs were not kibble fed and I think the whole evolution process takes a little longer than the time commercial doog food have been around! But they are my personal thoughts I guess, each to their own and its not for everyone.
Variety wise, just feed variety. Mine has allsorts within the recommended 80% muscle meat, 10% offal and 10% bone frame. Usually its chicken wings or pork and lamb ribs or spine for the raw meaty bone quota. I feed a mix of chunks or minced beef, lamb, turkey, heart, green tripe and sardines for muscle meat and kidney/liver for offal along with a couple of raw eggs a week.
There is a facebook group I use called raw feeding UK who are happy to give advice and have lots of info you may find useful if you do want to continue feeding this way 