2. Why there is a miner to download, when it is 100% PoS?
3. Is buying 1000 XEL the only way to earn more coins?
4. Where is the elastic computer in all that?
I am a bit surprised that you are asking these kind of questions. Obviously, you have neither read the whitepaper nor did you take even a quick look at the website. The information you are looking for is all there!
I installed the wallet and it all came back to me.
I used it about a year ago for testing some calculations on test net.
I remembered it by the dark colors (which I, back then, advised that need to be more readable).
Well I decided to give it a try once again. However this time there are two parts.
A Wallet and a Miner.
Wallet works, Faucet is empty. However the miner is not integrated into
the wallet anymore and a Docker instalation is needed. Unfortunatelly
I'm a Windows 7 user and Docker requires Win 10.