The introduction begs many questions. Could you please provide a photo that includes everything shown in the plan?

"Is there anything else I should worry about??" Actually, you should be worrying about the whole plan as it has plenty of undesirables.

A swale is a gutter-like dip in the ground (like a ditch, though it could be very shallow) and I'm interested in seeing what you are calling that. Where two houses are situated in close proximity, it's likely that the entire space between them would constitute a swale. Forget the plan for a moment. Suppose you contact the city and tell them you wish to build a concrete sidewalk connecting the front of the property to the back. What are they going to say? Your walk can only be 8" in width and it must abut the house? A swale is going to carry water away whether it is paved or not, so it's hard to imagine that the regulations are so strict for you and so lax for your neighbor that he gets a walk and you don't. There's a big disconnect here. I would not call the city, but go down in person and discuss with them, not your neighbor's plan, but strictly what you want to do in your own yard (build a walk from front to back.) I would not volunteer any willingness to build it of pea gravel. (And I would not build it of pea gravel or p.g. with stepping stones in it. It's going to be nothing but problems, especially if this drainage way carries much water at times.) I don't suppose there's a neighborhood drainage ditch running just on your side of the line so I'd ask the city again couldn't you build a normal concrete sidewalk -- of a normal width -- along the side of your house. If they say OK, you can. Then surely it could be deduced that a paver walk, as well, is permissible. Discussing your neighbor's plans with the city can only potentially complicate matters for you. Get your own clearance. Let him get his own clearance. And after you have it, then build it together if it pleases you to mesh your plans and do it that way.

Also, I would redesign your walk to get the wiggle out of it and leave more room for planting in the process. The small bed next to the steps is not a reasonable amount of room for plants. It would be better to have a simpler, more straightforward configuration to the walk. The little complications, as it now has, will not be cute but only make it look contrived.