Really nice looking example. Good description on the color variation. Could have been a stain at one point? I would say inconsistencies in the dye, but it appeared to have rounder, vertical "migration" which would lead me to believe it's not dye lots, but some sort of agent which may have been spilled on it.
Either way, it's a cool piece. Signature does not affect value, but is kinda nice. As the tag says, and from what I see, this is a Pakistan carpet. It's NOT a Jaldar, which is good news. Those are the double knotted rugs where the knots are tied around two warps on either side. They call it a jufti knot. But this is a regular symmetrical knot which appears to be wrapped only around 1 warp on either side.
Can't recall the design off the top of my head, but it's typical repeating gul field which probably has a proper name that I just can't remember
and then the question that always comes up ... How much?