There is a hose on your gas tank that connects to a metal fitting. Most likely, the hose just came off the fitting. Its common for that to happen. Crawl under there and see if you can see if the hose is off of it and put it back on

Thats like asking what size is a bit string,, everywhere will charge more or less.

You should ask this at the body shop.

Depends on the part needed, difficulty of getting into it and how much per hour the shops in your area charge as a work rate. For this reason, you should contact three mechanics in your area and get an accurate estimate.

So my check engine light came on today and the code came back saying that some hose that regulates the amount or pressure of gas in my car has a slight leak or hole. It doesn't really affect the car running but I'll have to fix it for emissions testing. I don't think its a severe leak because the light will go off for a while and come on again a few days later and its always the same code. About how much would it be to fix?