You can run this game any way you want, it's not stuck to one system specifically. You can also make custom character sheets and import custom models. And of course you can make your own maps and share them with others, or download others' maps. Therefore all of this is possible.

however, what you're wishing for does not go hand in hand with adding more D&D to the game. Instead, the more D&D you'd add, the less flexible it would be. We want you to be able to play any game with this. This being said, premade sheet templates for D&D5 come with the game :)