Mods can delete

I probably would given the info you've provided.

If you're at all interested in staying at your current place, maybe phrase it in a way that reminds him of what was said re: leaving and ask if anything has changed - that way it won't come across like F it I'm out, but rather that you really enjoy working where you are and are exploring other options based on what was communicated to you - can't blame you for that.

Have you discussed your career, where you want to be, any plan you have? Let him know what you are interested in and how you can go about reaching that goal. If you do have a good relationship, and he likes your work he may put you in touch with some of his contacts

I would wait until you get an interview. If you apply and don't get an interview, your application won't go beyond HR, so your boss' network wouldn't know. But once you get an interview, seems like it would be wise to be open with your boss and he might actually be able to help you get the job through his contacts.

Tell him. In this situation, the odds are much better it can help than hurt. That being said, when is your bonus discussion and payment? That could change my mind.

yea, just show him this post he'll understand

I say tell him. Everyone pretty much knows it's 2 and out anyways so he'd probably be surprised if you're not looking. I'd let him know that regarding your discussion when you were hired that he didn't expect you to be there for longer than 2-3 years and you're starting to apply/interview for your next step. Then during the ensuing conversation, you could even ask him if he has any contacts that you could talk to that might be able to help you get a position.