How does ELO Decay work in League of Legends?

I get different answers from different sources and really just want all the rules of ELO Decay with 100% accuracy. These are the the things I need covered.

• How long (to the day) without playing a Ranked game does it take for your Elo to decay?
• At what percentage does it decay?
• If you play a ranked 5v5 does it reset the Elo Decay timer for your solo queue?
• At what Elo does your Elo have the possibility to decay?

If your ELO is under Silver (1400) then you are unaffected by ELO Decay. Ranked 5v5 runs on a separate ELO system from your solo q ranked ELO from your normal ELO. from your 3v3 ELO. So anything you do in one does not affect any of the other ELO numbers.

Not sure of how long precisely, but I've heard it's 1-2 weeks you have to play a ranked game. It decays a flat amount rather than a percentage.

Elo decays over time when you are above 1400 after 4 weeks of inactivity at a rate of 25 per week in that particular queue. Each queue is separate so you have to play a 5v5 match to avoid decay in your 5v5 rating. It won't decay past 1400 rating.