There was recently a rotation to HS-EP. Also, I quit right when you did and just got back into it as well.
1. Because of the recent rotation, the metagame is still unclear. At Nationals, Yanmega Prime was the clear BCIF and it was used in a lot of various decks. However, Yanmega has a clear downside in that if you go 2nd in a Yanmega mirror you more or less flat out lose. A lot of the better players are moving over to slower decks running a Twins engine. This allows more room to outplay and a smaller disadvantage in going 2nd. This new approach at the game seems to have gone largely un-noticed despite all of the Top 4 decks at worlds using this approach. Some of the top cards will be Donphan Prime, Yanmega Prime, Zekrom, Reshiram, Zoroark, Emboar, Typhlosion (the last 2 with Reshiram) and Vileplume. I'm amazed nobody has mentioned Vileplume yet.
2. It's currently HS-BW but after prereleases are over (sometime next week) it will be HS-EP. Battle Roads will be HS-EP.
3. The new first turn rules. There are NO DRAWBACKS to going first. It now acts as a normal turn - you can draw a card, attach, play trainers, supporters and stadiums. Also, PlusPower is now discarded upon being played and not attached to a specific Pokemon. As far as deck choice, stage 2 main attackers are not going to be a good play. Trainer cards are now called items and Supporters are now Trainer - Supporters. You discard the supporter as soon as you play it now, which is just flat out stupid. You can leave it next to the active at the risk of getting small penalties (that's what I do) or you can turn it sideways in your discard until the end of your turn. Because of the already explained Rare Candy errata and no way to break normal evolution rules, running more of the basic card than the evolution has gained some popularity and it was the most successful approach at worlds - pyramid lines, who would have thought?
4. Pokemon Collector is still a staple. Pokemon Communication has replaced Bebe's Search. Unfortunately, we don't have a direct Uxie replacement - just like Uxie was the closest thing to a Claydol replacement in the format before it. For this reason, decks that can't fit Magnezone Prime or Ninetales have to run 10 or so draw supporters like Professor Oak's New Theory, Professor Juniper and Sage's Training. The format is very lacking in drawpower at the moment, unfortunately. Running a bunch of draw support creates tight deck lists. Also, Pokemon Catcher is staple. It will go down in price in a few weeks though, so don't buy it yet. A lot of decks run 1 Cleffa, although running more than 1 is unsafe. It's a popular donking target, but used for hand refresh when you have no other options. Junk Arm is staple and run in 2-4 copies. Reusing any item is just too good. Most decks are running 1-2 Switch. Other than than, it really varies by deck. Judge and Copycat are popular in Yanmega decks.