1. Hoopa-U is an interesting Pokemon. I definitely find it a huge threat that has the potential to get banned, which is why I voted for a suspect test for it. Personally, I don't think it's that bad, because it's slow and is forced to run a Scarf on Dark teams usually, which makes it predictable and without a Scarf it's easy to revenge kill because of that terrible defensive typing and bulk.

2. This ties in with the recommendation for new players - Smogon is a great resource for teambuilding. Look at the viability rankings, the ev spread thread, and creative sets. Build around cores or Pokemon that you like and add Pokemon that support that Pokemon. After you're done building the preliminary team, test it as much as you can and make edits. The best teams are made from consequent testing and editing. Don't worry too much about EV spreads, think about that when you've perfected the rest of the team. Try building around underrated threats or Pokemon that you think are cool (but still viable), and you'll probably have a team at the end that you like more.