As for gouramis they tend to be decent community fish with the standards being semi-aggressive and the dwarfs being more peaceful. Temperament can vary from fish to fish. The dwarves tend to be what you find in fish stores with varieties like flame, neon blue, and powder blue being the staples. Giant and kissing gourami are less common in stores. The dwarves pair well with tetras, mollies, platies, rasboras, danios, loaches, cory cats etc. Avoid semi-aggressive species that will stress them out like barbs and cichlids. There is always exceptions and your mileage may vary. I'd suggest adding a pair of gourami once your tank is cycled and then start GRADUALLY adding tank mates. If a new tankmate doesn't work then pull it and bring it back to your LFS
. Even if they won't refund you it's better than having conflict in the tank. In a larger tank like a 75 you should have no difficulty building a balanced community around a pair of gourami. When in doubt, ask the community like you're doing now. Good luck and welcome to this challenging and fulfilling hobby.