Newbie with tech questions. HELP please

[Prince50]

Just bought my first H1. 1995 4 door pickup 6.5 non TD with 67K miles now.

Bought it last month with 64K but drove it home and have been driving it since.

Anyway, to my questions.

1. When driving at specific speeds, the oil pressure drops to 10 PSI. If I adjust the speed to 62 instead of 65, it returns to 30 PSI. What gives?

2. every once in awhile a pump sound like the CTIS pump starts inside the dog house just behind the AC controlls or radio. It does not matter if the AC is running or not, it just does it. It will run for 4 minutes or less then stop. What is this?

3. Occasionaly, and more often in the last few days, there is a burp sound from the passanger side dash area. It seems to do it at random, and does not care if the AC is running or not. Just a short BUURRP!

4. AC seems to drip all its condensed water into the cab by the passanger foot area. Normal? AC blows cold, so it works just fine, and the drain plug lets it all out. Should I be doing something about this?

5. I have a stud in the split rim that has popped. I cannot even bang the broken stud out with hammer and chisel. Am I doing somthing wrong? I have the replacement, with nut, and penta head socket to reinstall, but am stuck at this point.

Thanks in advance guys.

Darin