Having just put my dash back in.......... again, I can say for sure, that the 4 bolts near the defroster vents are for holding the dash frame to the firewall, not the pad to the frame. One thing to keep in mind though is that, in addition to taking out, or dropping down the steering column, it will make things easier if you actually remove the threaded studs that are used to hold the column up. The studs are just threaded rods, 1/4 x 20 x about 4 inches I think, and with them removed, all you have to do is allow the dash to swivel downward/inward (after removing the upper bolts) on the lower side bolts. You don't have to take out the lower side bolts and in fact, it's much easier if you don't. Just loosen them up. With the column studs in place, I had to remove the left side , lower bolt to allow the dash to go over the column studs, then move it up again once I got it into the right position. After getting the dash over the studs, I had to fight it back into place, then try to restart the lower bolt. To reinstall, without the studs in the way, just rest the lower dash brackets on the lower bolts, pivot up and then fight the upper bolts in place. Real easy to screw the column studs back in their holes after all that.
One final thought.............. have a flexible magnetic pick up tool handy for when you (and you probably will) drop at least one of the upper bolts while trying to reinstall them. My fumbly fingers just didn't want to allow me to work in a tight space without a few choice words and some contortions of my body to try to recover the upper bolts before they were lost in the confines of the area between the dash frame and pad.
All in all, I have to finish this by saying that I am REALLY glad that my dash is now in............. for the last time. What a pain in the @#$ that whole mess was.