I'm in agreement here -- the long curved line across the sheet, especially, is almost certainly due to getting into the developer unevenly. Also, is it possible you pulled the paper after a lot less than the full development time (typically 2 minutes in Dektol 1:2, 68 F)? That will give a muddy appearance, where the shadows (or in the case of a paper negative, the highlights) aren't fully developed and are gray instead of black. And you have a lot of fog -- for which others have made good suggestions.

The mottling looks very much like an effect I once saw when trying to contact print paper to paper to get a negative print, caused by variations in the density of the paper and/or the reflective backing behind the emulsion. Is it remotely possible you could have exposed the backing side of the paper, instead of the emulsion side? Under safelight, most papers are glossier on the emulsion side, but a few matte surface RC papers are actually shinier on the back...