Personal opinion: Silver Sharks are the worst fish I've ever had the displeasure of dealing with (my father owned several) and I work in a fish shop dealing with hundreds of fish every day. You couldn't pay me enough to have one in my community tank. Extremely easily spooked, notorious for jumping out (through lids or without), grow extremely large, prey on small fish such as tetras, rasboras, etc. I never, ever have recommended them to anyone and consistently talk people out of buying them.
Dwarf gouramis can be prone to issues with bacterial infections/iridovirus so try to get ones sourced from Australia only, not imported. If the shop can't tell you where they came from, don't buy them. If you see any with a bacterial infection (google for pics), sitting in one spot looking sad, hanging on the bottom or the surface then don't buy ANY from that batch. They will all turn out exactly the same. This does not apply to Honey Gouramis and 'Red Honey' Gouramis or whatever they're called. They're a fairly new hybrid between honey and one of the other dwarves so the naming varies a bit. They seem to be very hardy too. And of course doesn't apply to ones sourced from Australia as I've never had an issue with any of those.
Either go for 1 (better choice for your tank) or 3+ when it comes to Gouramis due to territorial issues.
Cories need a group to be happy, 4+ is ok, 6+ is heaps better. There are plenty of much nicer ones out there than the Bronze that will be more suited to your tank size. Panda, Pygmaeus, Habrosus, Hastatus are all good choices. Julii is probably the biggest I would go with and then only in a smaller group of 4.
Rasbora are fairly hardy and do well in groups of 6+. I wouldn't have a problem putting smaller Rasbora in your size tank. Harlequins are probably the absolute largest I would go for. Similar, better suited size wise options would be Ember Tetra (Hyphessobrycon amandae), Rasbora Maculata (Boraras maculatus), Rasbora Espei (Trigonostigma espei - IME stay smaller than Harlequins despite what many books/websites say) and Glowlight Rasbora (Trigonostigma Hengeli, same thing as the Espei).