If you are sure about the rotation arrows do not drive that anywhere other than your nearest tyre fitting place and do that carefully!!!
Nexen's, as far as I know are budget tyres and I can't comment on their ability as I've never had them, maybe someone else on here has Also don't know enough about them to know if 6000 and 8000 are acceptable together, the golden rule is to have same make and type all round though.