that is the worst title you could have chosen for this topic.
as for the subject at hand, the way they mine Monero is through running mining scripts on websites that you visit. for example ThePiratebay.org used to have this in the background and whoever visited that site were mining for them for the duration of their visit.
it isn't a malware that installs as far as i have seen.
Bitcoin can be used just the same, and that kind of malware is present for any kind of shitcoin, not just XMR.
no it can not because coins like monero are being mined with GPU but bitcoin needs ASICs to be mined efficiently. mining through browsers from people' GPU is not going to get you anything.