SEO/domain question

If I want to rank for a certain kw, does it matter if there's a word before or after? and are these equal?

For instance, kw.com, kw.org, kw.net are all taken, however there's kw_____.com and _____kw.com available. Will google recognize both of these as equal if I try to rank for that kw?

You want kw's as close to the front as possible (so I was told...who knows with G?).

my vote for kw_____.com, then k-w.com, then ____kw.com, then k-w.net/org