I'd recommend either the Springfield Single stack (xds) or the S&W M&P Shield. Both use a single stack of ammo making the entire handgun thinner which reduces the weight and makes it easier to conceal. I've used both and they both work as expected. The down side is the limited number of rounds a single stack can hold.

Your best bet for a holster would be to pay a little extra and have a custom holster made. I don't think you are going to find a good off the shelf holster to use on a bike.

As a fellow C&C holder I'd rather get a black eye and have my bike stolen than shoot someone. Please don't misunderstand, I could care less about whether or not the assailant walks away, I'm more concerned with the attorneys fees and possible civil lawsuit. Additionally, you would need the assailant to give you enough time to identify them as a threat (usually requires training and superb instincts), react to the threat (access your handgun) and make them aware that further action will have consequences. If I were going to rob a cyclist I'd sit in the bushes and stick something in your front spokes as you rode by. Again, this isn't an argument about guns, it's about the efficacy of carrying while on a bike.