It’s nigh impossible to get all one gender as most are sold before sex is apparent. The only way is to go someplace with older shrimp and specifically select out grown females. I’ve had one that way.
If you don’t want breeding, Amanos might be a better choice.
But have you tested your water’s KH/GH amounts? I advise new folk see which species their water supports before choosing. It may be your water’s KH and GH are in Neo healthy ranges. But if not, better to know beforehand. Sadly test kits aren’t typically at pet shops, need specialty aquarium store or order online.
You are on the right track: more plants. Do not worry if there is algae growth, shrimp love it.
Do not worry about reproducing, it’s amazing how many shrimp you can have in a tank.
If you can: buy your shrimp from a local breeder who doesn’t try to adjust KH, GH etc., so that the shrimp you get do not require special water treatment
Effective_Sympathy_6 
It’s nigh impossible to get all one gender as most are sold before sex is apparent. The only way is to go someplace with older shrimp and specifically select out grown females. I’ve had one that way.
If you don’t want breeding, Amanos might be a better choice.
But have you tested your water’s KH/GH amounts? I advise new folk see which species their water supports before choosing. It may be your water’s KH and GH are in Neo healthy ranges. But if not, better to know beforehand. Sadly test kits aren’t typically at pet shops, need specialty aquarium store or order online.
You are on the right track: more plants. Do not worry if there is algae growth, shrimp love it.
Do not worry about reproducing, it’s amazing how many shrimp you can have in a tank.
If you can: buy your shrimp from a local breeder who doesn’t try to adjust KH, GH etc., so that the shrimp you get do not require special water treatment