stocking help for newbie

[Andy578]

looking for some help figuring out what i can put into my tank. i have a 36" 65 gallon currently sitting waiting to cycle. i have well water that is naturally fairly hard and higher ph which from what i can tell would be perfect for cichlids so that's what i'm leaning towards. i was hoping to get some that are fairly peaceful and in the 4-6" range once fully grown. problem is there's just so many different types i get confused fairly quickly while researching especially when you start comparing the different lakes so really at the end of the day i don't seem to be retaining much information. realistically how many could i safely keep? i was hoping somewhere in the area of 10 but i do want to be safe and try to avoid issues so maybe that's pushing it for this tank? does gender matter and if so can you actually reliably sex them when they are small?

also the lady at the pet store claimed that it would be safe to keep a pair of rainbows in a community tank so i'm open to that route too but their advice has proven to be wrong several times so far so i don't know if that's true or not.