You are now limited to carry 2 pink wards at all times, and only allowed to place 1 at a time. Play around the trinket system & Sight Stones, the new vision system takes some time to get used to.
Theres lots of new GP+5 items, Of course, Heart of Stone & Philosophers stone are no longer in game. Keep in mind you are only limited to 1 gold generating item.
You can't buy jungle items if you don't have smite, and smiting large jungle camps gives different effects.
Lots of new items in game, might want to go to LoL's website and slowly go through them. Go through preseason rundown videos for seasons 5 (or patch-notes for 4.21) for jungle changes (of course, look up the preseason 6 rundowns as well)
New support (though not limited to support) champions you might want to look at:
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Braum (burly guy with a giant shield that blocks all projectiles)
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Bard (fat chubby celestial being that only uses trumpets to talk. Oh, he gives you a magical journey as well and an AoE Zhonyas affecting everyone)
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Tahm Kench (Catfish demon with a big mouth, make sure you taunt your enemy champions, hes nearly got a line for everyone! Also, he can eat enemies / team mates)