400ex blown head gasket ? Broken valve cover bolt?

Ok so I've noticed that my 400ex has some oil smudges on the cylinder in the head gasket area. I don't know if you guys could tell from the pictures but is the head gasket blown? It doesn't blow smoke from the cylinder. I also feel that my bike lacks some power towards the top end. Probably time for a rebuild? And one other thing I've noticed is that I have a bolt sticking out from the valve cover I don't know if its broken. It probably if because I tried tightening it and it would just spin. I've never opened up the engine but I think the previous owner probably did. And one last thing I've noticed is that's bike takes for ever to warm up when cold. And when I ride for a good 10-15 minuets my bike gets hot and stays hot for a while even when it's turned of. Thanks for any help and sorry for the long story lol.