I had the same issue last month. I sprayed soapy water all over the windshield and used air on the inside of the windshield to find bubbles after I cleaned the sunroof drains. I ended up having a bad windshield seal. Fixed the seal and no more water in the cab and no more random horns.
2001LC do you recommend the McMaster clamps for reclamping the inner small boots? If so do you happen to know the part number of the ones you recommend?
Have a similar problem as well. Inner boots on both CV axles had grease around them. Couldn’t find any holes. Cleaned the axles and will drive to see if they start throwing grease again. Hopefully you can get yours fixed easily. I’ll post an update on mine once I find anything.