If your hamster is scared and timid, why would you put the stress on him of forcing him to meet with something he is terrified of? Plus, even the friendliest dog can get carried away and try to kill the little hamster. If the hamster is scared enough, it can even die of stress alone. Also, if a hamster feels threatened, it can take a hearty chunk out of a dog's nose, which would it certainly provoke the dog to bite.
Not a good idea. The only time they should be together is if the hamster is in a hamster ball. Otherwise, he is fair game for the dog and you may end up with a hammy snack.
Do not put your dog by your hamster! Chances are the hamster is probably really stressed or something and your dog could unintentionally hurt your hamster. I wouldn't even put her into her ball with him around because dogs can get into a hamster ball really easily and it is not worth the hamster getting hurt, or even more timid.
keep the separate except when the hamster is in its ball. unless the dog enjoys chacing balls in which case avoid that too lol.
my dog is scared of my hamster. he always hides when he's in his ball