g1smd - 7:58 am on Jan 30, 2013 (gmt 0)
I am wondering if this issue is merely a cosmetic alteration to the address bar
No. The browser address bar shows the URL being requested, and it's malformed.
There's several ways to tackle this.
The most obvious is to have 5 rulesets: one for a, another for a and b, another for a and b and c, ...
The other way is to not redirect in htaccess at all, but instead rewrite (that's rewrite, not redirect) the requests to a PHP script that works out what the new URL will be and then uses the PHP HEADER directive to redirect the browser to the new URL. When you do this, the rule needs to be high up the list of rules in the htaccess file and you need to add the PHP filename as an exclusion to the non-www/www redirect otherwise non-www requests with parameters get re-exposed with parameters at www instead of redirecting to the friendly URL.
It doesn't matter which method you use: htaccess redirect or PHP HEADER redirect after internal rewrite. As long as asking for URL with parameters returns either 404 because it's invalid or 301 to the new URL, the process is sound.