floor noises supposedly from plumbing?

[David Oxhandler]

It is not necessary for the toilet to be 100% perfectly level.

If a portion of the wax ring was missing it is possible that section of the wax was stuck to the bottom of the toilet and you may have squashed it down under the new ring... if this is the case then the toilet would not sit flat on the floor and seem more out of level than previously and yes might very well leak, If you did install a new toilet at that same time you may have other issues in matching up the toilet and flange. You may need to replace the flange.

This Old House web site has an excellent tutorial on toilet installation you can see here --> http://www.thisoldhouse.com/toh/how-to/ ... 52,00.html