CUB149'S PROFILE

So I'm starting to make a game, and I got some questions while starting.

First, is it generally accepted to use premade graphics + the DLC to make a legit game? I don't wanna just look like some cheap guy who just uses other people's stuff.

Secondly, about how long do people generally spend on their games? I intend to make mine about as long as adventure games in the vein of The Crooked Man and Mermaid Swamp.

Finally, how often do people actually use the RPG-battle part of the maker? Most of the games I've seen are like the aforementioned survival-horror games, without many actual battles.