It is very difficult to detect the virus especially if it was being hidden by the mining software that you have downloaded. Antivirus is your only option to detect them so it will be best if you will install the top ranking antivirus in order to lessen the chance of any virus to bypass it.
It is, actually. Remember that we're specifically talking about mining here. It's easily easily noticeable if your device is unusually using up too much unnecessary power especially if you aren't even doing anything that resource-heavy.