Where did my ability go!?

I haven't played for a little over a week. As expected, I was rusty when I came back to play. The last 3 games I played that I won before my break, I played ADC and played well, for my bracket. I was winning somewhat more consistently and I was climbing. I am currently Bronze II with 0 LP, probably on the verge of getting demoted.

When I come back, I'm not only rusty - I'm horrific! My cs suffers, my team says I'm just a bad player and I should uninstall, and when I try to make a play, it backfires on me instead and I die. I'm an adc main. In my last few games, I've had a Malphite that started Ancient Coin as my support. Isn't Targons the best item for tanky supports? For example, Thresh would get Ancient Coin cuz Targons is hard to proc, and Talisman of Ascension is good on Thresh in general. I had a support Morgana who was playing well, but rather than building even remotely tanky like RoA, Rylai's, she just went straight AP and wouldn't contribute to teamfights like she should.

Here's some issues I know I have:

With Ezreal, whom I love to play with, I don't know when to build T-Force, Blade of the Runed King, Iceborn Gauntlet, Last Whisper, or maybe Statikk Shiv? I've seen it's good for his harass and waveclear, although I never buy it. I heard Infinity Edge is stupid on him because he relies more on his Q than auto attacks, and Q doesn't crit, does it? General itemization advice, I guess.

With Caitlyn, I've always started with Q, got E at lv 2, W at lv 3, and my playstyle has been shaped around that. Recently, I've been told that starting W and leveling W then E then Q are the best because they provide the most area control and the cooldown for E will provide more critical attacks overall due to her passive procing on E hit. Is this always true, or should I level Q first against some matchups? Anyway, if you view my match history, you'll see why I'm dying on the inside, and people want me dead on the outside.