It would be wise to either trade them in TCGO for cards you need for decks or selling them. I don't recommend opening them, you'll get a short time of fun but nothing else.
Probably. I find that I have six hours of league time and then am wanting to play with someone the other 162 hours of the day. It’s good for being a Pokémon addict, but if the six hours is enough, go for the trades. Or, even better, give em away.