Need advice on converting Multiple Movable Type blogs to WP

This weekend I got sick and tired of my Movable Type blog, and decided to finally make the jump to WordPress.

I am following the instructions on how to import from MT. However, I’m very nervous and would like some advice on how best to do this. Specific questions are in bold.

Right now, I have three blogs run from the same database. I have exported all three into three separate text files. Their current locations are:
https://www.thehutch.com
https://www.thehutch.com/monitorduty/
https://www.thehutch.com/melinda/

The Monitor Duty blog I’m going to put back into its own domain, MonitorDuty.com. It used to be there, but when I put all my domains under TheHutch.com, the subdomain thing caused the Monitor Duty blog to format improperly. Now, with the WordPress blog, this shouldn’t be a problem. Of course, I may have to fix hundreds of links. Which brings up a question:
Is there any kind of bulk find-and-replace? I don’t see one, but WP is very new to me. Perhaps there is a plugin that does that?

Should I do three separate installations, or two?
In an ideal world, all three could run from the same installation, since they’re all part of TheHutch.com. That way, I wouldn’t have to duplicate the plugins and a lot of settings. However, I’m going to split Monitor Duty off to its own installation just so I can have it be its own domain again. The question is, can I run the remaining two blogs, (thehutch.com and thehutch.com/melinda) from the same installation so that we can use the same templates and plugins? Any advice on how to do this would be useful.

Thank you!