I've never tried to change departure dates, and I doubt most agents would let that fly with the relatively small schedule changes you mention.

I've also never changed origins, but they may go for it if there is availability. The automated "online rebooking tool" for travel advisories often lets you select other airports in the same metropolitan area.

I have changed connection points before.

YMMV on all of this, but it doesn't hurt to ask for what you want. Have something ready to propose to the agent rather than having the agent select something for you. Have alternatives ready as well, or be prepared to call back and try another agent if you're not satisfied. Another agent may be more flexible or simply confirm that your proposed change cannot be accommodated. For what it's worth, I've always been able to resolve schedule changes to my satisfaction.