Well, you learns something new everyday.
I think my major mistake was not clearing the cached CSS via the Refresh option "Clear Private Data" each time I made changes. Now that I've found that option I use it each time.
I've resolved the text-align problems by having to create special CSS classes to use in the <th> & <td> tags that simply do "text-align:center" or "text-align:right" -- inserting style attributes in the tags themselves or in the computed text within the tags had only marginal effect even when "!important" was added. XPiNC is a little finicky and persnickety to be sure.
Adding the ExtLib Firebug Lite custom control sure helps too!