Yes it should still OC, the OC version has been tested at the spec they set for it and will normally still have OC headroom above and beyond the spec. I've got trhree Strix cards and those as well as all I've used in client builds OCed above and beyond
Its just factory overclocked, so the boost and base clock will be a little higher. Yes you can still overclock it. I dont believe it is even binned higher on the OC one, so it shouldnt effect any overclocks you do yourself.
Yes you can just overclock it yourself; the OC version may have a better-binned chip that is more suited for overclocking, but you can only know by trying.
Yes it should still OC, the OC version has been tested at the spec they set for it and will normally still have OC headroom above and beyond the spec. I've got trhree Strix cards and those as well as all I've used in client builds OCed above and beyond