Suggestions...
Set Artist as you want, to First Last.
Leave Album Artist blank, except in cases where you want to assign a single Artist to a multi-artist compilation disc, such as a soundtrack, or a disc that is primarily one artist but contains a couple of exceptions. There is an automatically calculated field named Album Artist (auto), that uses the values of Artist to determine if an album is a Multiple Artist album, but will use Album Artist when set. Several areas of MC use Artist as a shorthand for Album Artist (auto), and this drives views, headers, etc.
Create a new use-defined field, called Artist (last, first), and assign your Last, First names there. This way, you can use Last, First how you want, and use First Last via Artist and Album Artist (auto) normally.
http://wiki.jriver.com/index.php/File_Properties_%28tags%29To assign the result of column 3 above (the expression that re-orders), just tack on an '=' character in a field's edit area (Tag Action Window, or in-column editing):
=If(Regex([Artist], /#^(\w+),\s(.+)$#/), [R2] [R1], [Artist])
To assign your Artist (last, first), select any tracks for which Artists is currently formatted as Last, First, edit Artist (last, first), and assign:
=[Artist]
For those Artist values that are not in Last, First order, create a 4th column in your view, and set the view to the following simplistic expression:
if(Regex([Artist], /#^(\w+)\s+(.+)$#/), [R2]/, [R1], [Artist])
This is very rudimentary, in that it just moves the first word to the end of the phrase - it does not deal well with such artists as "Mumford and Sons", so you'll want to use it selectively. The view should help. We can make the expression much more complex to handle many of the cases, but it may not be worth your while to spend so much time on this. Let me know what your needs are.
You can use the 4th column expression to assign the values, just like above.