You should buy a premium domain if you need to run a good site/business .tk free domains are not trusted.
I get a really bad feeling about .tk websites...seeing as crypto currency is centered around computer science and the such I would advise everybody to be careful visiting links like that. You don't want to stumble upon a website with an exploit kit executing code of an encrypted botnet on your machine. Maybe I'm freaking out but I don't click links in general for those reasons.
You are probably freaking out. only visiting or clicking links like that don't effect you and your system anyway. lots of blogspot or wordpress sites hosted on .tk domains.
Yes. some people use this .tk to share virus but not everyone..
BTW OP should buy a premium domain for business purpose. this dot.tk domain can be only good for mini bloggers.