One of the threads on my hub bolt (passenger front) is really messed up. It took about 45 mins to get that lug off and is basically unusable. I'm going to drive to work tomorrow with only 4 but how safe is it? How hard/expensive is it to replace those hub bolts?

 

You"ll be fine i rocked 3 lugs on my 2.2 for months..

 

Replacing one is not hard at all. Get a wheel stud from Autozone for a few dollars.

Take a hammer to the old one and hit it so it pushes out the back side of the hub. The new one goes in the same way the old came out. Take some washers and then use a lug nut to pull the new stud into place from the threads.