How many times a day should I feed my fish ?

It is fine to have those fish in because as long as there is harmony and no eating of the other fish its fine. You should feed them twice a day with a mix up. and you should feed the pleco tiny pieces of cuber or you can buy algae pellets for him. also the pleco WILL NOT out grow your tank, never. It never gets bigger than the tank it is in. and 25%-50% change per week is fine