League of Legends (LoL) Question: Need a quick reboot

Hello. My final year in school (and therefore the final exams period) is over and I will now start playing again.

When I left the game, I was silver 3 and the reset of the rankings sent me back to my hated bronze 3 (the division from which i started playing rankeds).
I moved up to bronze 2 quite easily (you know, just using snowball champs) but I would really like a quick introduction to the current meta.

So, is it a tank oriented meta or an assassin one? Is there any major differences regarding objectives in the game (like dragon/baron being buffed/nerfed). Also what role is currently overpowered (ex. I remember about a year ago, junglers controlled the whole game)

Finally the following list includes what I used to play

Rengar top lane
Shen top lane

AP Tristana mid lane
Lulu mid lane

Shaco jungle

Graves adc
Ezreal adc

Lulu support
Alistar support

I would like to know is any of the above mentioned champions not viable anymore or not viable in the said role.

Thanks in advance.