I love this stuff for a lot of things but for this it's too stiff. This will be a tricky repair job, might be an idea to take it to a shop. Every time I've tried this the cone gets out of alignment and makes noises afterward.

I have had excellent results with Gorilla glue. Stpaulguy's source is probably better, though.

Go ahead & use urethane. It will work fine. I use 100% silicone for the same issue with good results.

Probably, I use it for a lot of things and keep a tube of the primerless urathane around.

I wouldn't. You can buy new foam and the proper adhesive from these guys

http://www.midwestspeakerrepair.com/

My Alpine R10's surround has come apart from the basket in a few inches. I tried superglue but after a few good notes, it failed. My idea was to use windshield urethane to glue it and the rest of the surround (preventive maintenance). Any reason this is a bad idea if I'm careful in applying it?

-Thanks in advance!