I think you have it backwards when you say “see if I need only a capable architect or should I consider a structural engineer + architect?” I would say that you need a structural engineer for sure and only need an architect if you need help with … architecture, which is how the finished product looks.
The structural engineer does the bulk of the drawing that are used by the contractors. Try a guy named Bruce Cosart and ask him if he would be willing to do your structural drawings with no architect involved. Maybe borrow his draftsman to do layouts and site plans as well.
The architect only draws the layout and designs architectural features for look and feel / functionality / roof lines and styles. If you just want to match the existing exterior look and are adding a simple square space, then you can probably get away without an architect. A good architect will also know setback rules, height rules, where outlets need to be legally, help with a lighting plan, make sure you conform to fire codes inside and out, and possibly do something more aesthetically pleasing than a simple square bump-out that. A bump-out can give you a patio roof opportunity, too. A kitchen designer could be a good replacement for the architect, too. The ones at Home Depot aren’t so bad if that is where you are getting cabinets but I think you have to go to the design center now. We DIY’ed all of our interior/kitchen design and used IKEA cabinets for low-visibility cabinets behind the island. I wouldn’t hesitate to put IKEA cabinets in a kitchen at all if the look of the faces fit your style. I would fully design the kitchen before deciding on a size and shape for the remodel.
Once you have a layout and elevation drawings, the structural engineer will do structural drawings and you are ready to go to the permitting folks. This is a good place to pseudo DIY it. The suggestion of using a permit runner is a good one. Try Ron at Sunshine permits and he can work with you or your engineer/architect to submit drawings and get feedback from the city and make changes. Ron should know expected timelines.
If you want the contractor to do the drawings, find a design/build company. Usually their architects and designers suck but they know how to get drawings together and pull a permit. Maybe try K-Co in Clairemont. They may not help you if you are very far out of Clairemont but they might recommend someone.
