What kind of spider is this and is it dangerous?
That's a nice female Nursery Web Spider, related to the Fishing Spiders.  They're rather pretty animals, and like almost all spiders, quite harmless to anything that's too big to eat.  The very rectangular cephalothorax ('head' end) pattern and the simple wavy line down the abdomen are the key clues for this one.  They also like to sit with the front legs arranged in pairs.
https://bugguide.net/node/view/2919/bgimage