Mine smells too but I just figured that’s what happens when you run something that zaps the air. It’s not like it’s gonna kill you or anything, just crack a window if it bugs you. Works fine otherwise.
Just grab whatever cheap AAs you can find. I think I’m still running the ones that came with mine and it’s been months, so it’s not like you’re gonna be swapping them every week.
If your water pressure is decent it’ll shift normal dirt well enough. If you’ve got proper caked-on algae or years of grime though, you’ll still be out there scrubbing. It’s not a pressure washer, it’s just a better nozzle. Manage your expectations and you’ll be fine.