Re: bearing in mind that my Thor knowledge is limited to Simonson and some Avengers...
Interesting...
Whither Thor possesses the Odinpower is an important factor, it's presence makes WW's victory unlikely. Since with it, Thor is more then an equal to the Gods.
Strength? Also hard to gauge, Whither Thor is an equal to Supes or Captain Marvel is up to debate. Thor has stated that he only fights mortal foes with one-third of his strength. Would he consider WW a mortal foe or more godly? Thor has stood toe-to-toe with the Hulk, Hercules, Juggernaut, Wrecker and other +100 class foes. I don't know enough about WW's strength levels to compare. I'm assuming she's at least +90 class. (+tons)
Since both have vast levels of combat experience, strength is less important then other fights. Your comment on WW's speed is really important, since I think she faster then Thor. (But he might counter that moving speed with lightning teleportation)
Worthy-of-Mjolnir? A thinker, because WW is certainly worthy of carrying the hammer but while Thor is awake and not one the ground? I'm a little uncertain on the current rules but even if WW grabbed the hammer mid-flight, Thor could probably merely summon it back to him.
Lasso: How would this affect Thor? Magically I mean. Thor is virtuous and honest, does that revert the lasso to the role of unbreakable rope?
I think (and agree with you) that WW's best chance is to keep the fight moving, try to lead Thor into a tactical trap. If she stands toe-to-toe, she's not going to take it. But Thor often thinks with his heart, he underestimates WW or her weapons, he might be toast. He's also in trouble if he loses his cool. From what I've seen of the two, WW has a better track record of keeping her focus.