Thinking about adding a family room and updating the interior, where do I even start?

We’ve outgrown our little place near College Terrace and instead of moving in this market we’re seriously considering a home addition and interior remodeling in Palo Alto CA. The plan is to bump out the back for a family room and then refresh the kitchen and both bathrooms while we’re at it. Sounds simple enough until I started reading about permits, setback requirements, and how long the whole thing might take. Now I’m second guessing everything. Do we hire an architect first or a contractor who can bring their own designer? How do you even budget for surprises when they open up walls in a 1950s house? I’d love to hear from anyone who’s done a project like this around here. What was your timeline, and did you end up living on site or moving out? Also any advice on keeping the neighborhood happy during construction would be appreciated because our lot is pretty tight and I’m already stressed about the noise and the dumpster situation.