Rooting and installing a custom ROM are two independent things, you don't need one to have the other.
Rooted devices can use the official Play Store yes, though most people use Aurora Store to access the Play Store because they tend to remove Google Play Services from their phones as well.
Rooted devices can use the official Play Store yes, though most people use Aurora Store to access the Play Store because they tend to remove Google Play Services from their phones as well.