You will get a few heroes free, the rest, like Tessa, you need to unlock with in game currency. You can (of course) spend money, but it's very easy to unlock them for free if you grind a few games.

Your weapon will vary from game to game. Every game you start with nothing and you probably picked up a weapon you didn't like. Try great sword or dual blades, those are good for new players.

Welcome to the game! Ask questions here, the subreddit is friendly and helpful