Out of your ideas I like #1 and #4 the most, for #1 I pictured a bunch of animals dressed up as bakers too after he hires them/gets their help. Then for #4 I imagined the Patissier slowly noticing the animals in the pet shop getting more chubby as they eat cakes maybe?
I really like your idea of the animals dressed up! I think that plot might be the one I'm heading towards
You should definitely check out 'Prep and Landing' it's a really cool short film about how Christmas elves prep the houses for Santa to deliver presents, something like that could really work well for you in terms of the 'animals delivering cakes' idea. This may be too convoluted for a short animation but what if the animals that are trained at this particular bakery are forced to either train a new animal to deliver the cakes in a quick and sufficient way, or the baker has had to move location and they now have to adapt to their new surroundings, a 'fish out of water' kind of story so to speak.