"I have feeling that their is a leak somewhere in the house." ??
It would help a lot if you could say what makes you think that.
The other two things sound like nuisances, but are probably harmless - unless the floor under the shower has rotted. Chances are, the floor of the shower is just not supported properly and it's not hurting anything.
[This message has been edited by rpxlpx (edited July 19, 2002).]
It would still be a good idea to check everywhere you can for any dampness. I would look under the house if there is a crawl space. If you can't find any indication of moisture, I'd not worry any further. Just my opinion.
I'm on my third used home, so I have a LOT of experience in making repairs to neglected homes, and in homes that were worked on by people who thought they knew what they were doing, but clearly didnt. Like using 12/2 NM for a 220 connection to the well pump, NOT GOOD. This house I have now, the plumbing they put in for a new bathroom was put together so poorly that I was able to take it all apart without breaking anything, and it was all PVC DWV!