Get header STUDS, they make installation an effing breeze and hold torque much better. If you do get bolts get the stage 8 jobs and prepare for hilarity when one of the C clips flies off somewhere and you can't find it. Ask me about that one...
Header studs are awesome . On a 5.0 I think long header bolt are a joke there so easy to access the key factor with headers is to tighten them run the engine to operating temp, let cool then re tighten then put a few hundred miles and go over them . They shouldn't come loose after that . Doing the above I just mentioned never had a issue with header gaskets with the stock gaskets that come with the headers . Just my opinion
header studs for sure esp if you have aluminum heads. As for the gaskets, I had issues with the cheap ass fel pros blowing out, and same with alumimum ones, I only use the copper gaskets anymore.