Although downtown is IMO not the optimal area for either shore diving or finding buddies (that's the north end resorts) one that meets all your criteria is:
Dive Hut Bonaire - at night walk over to Karel's Waterfront Bar and talk diving loudly.
IMO the optimal place to find a buddy is Buddy Dive. Just about everyone there is a diver or staying with one. If you can't find a buddy in their bar you're not trying. It's also about the best for shore diving elsewhere with the drive-thru tank pickup. But you won't like the single supplement price - it's about $600 extra/wk.
Welcome to the Buddy Dive Resort website
Just north of there is Habitat, the other original dive resort. I was asked twice there (only visited twice) while waiting for mine.
http://www.habitatbonaire.com/
Maybe Eden Beach slightly farther south also. It's smaller, has WannaDive onsite and Bongoes beach bar for finding buddies. My subjective opinion is that they cater to the Dutch/German crowd. They seem to have gone more upscale recently so IDK if it's still a good value.
http://www.edenbeach.com/index.php?lang=en
In town there's also the Divi Flamingo - it's pretty close to an AI dive resort - they have meal plan options. I don't know it well enough to comment on availability. One of few dive resorts you can walk to downtown from.
http://www.diviresorts.com/diviflamingo/
Carib Inn is a smaller dive-focused resort just south. Probably more reasonable. Bruce is the go to guy on Bonaire if you have any gear that breaks while there.
http://www.caribinn.com/ No restaurant but you can walk to several from there.
South of there is the Plaza - they offer the only real AI dive package on Bonaire. Kind of spread out but even if you don't stay there, go to the Beach BBQ on Tuesday to find other divers. My impression of the Plaza is a lot of non-divers stay there also. The ScubaBoard Bonaire Invasion last year was held there.
http://www.plazaresortbonaire.eu/en
There's a lot of affordable smaller apt. rentals both in town and south in the Belnem area. While most bundle dive packages many aren't on the water so I don't think the odds of finding buddies would be as good. Belnem is generally pretty quiet at night.
Coco Palm Garden is one affordable option there - across the street from the water. Unless you find buddies there you won't find them nearby - it's all residential.
http://www.cocopalmgarden.org/CocoPalmEnglish.html
Your flight inbound is a good option. We met three groups while waiting for our flight to be called (my buddy wears dive t-shirts on planes) one turned out to be on our boat that week, another we passed 3x at shore dive sites and the third we never connected with.
hth, anywhere there's a crowd they're likely to be divers. There's not a lot of other reasons to go there.