I presume your "Tail Indent" format results from a difference in right margin settings in the source document and your OmniOutliner document.
For what exists, can you not take one of the offending entries, reset the margin to what you want and make it a named style, then apply that named style to the other entries ... or would that only work in OOPro and you have OO. I've not tried it personally ... just thinking.
The other thing is, when pasting in information from another source, try "Paste with Current Style" rather than just paste.
Any good?
Mark