Agree with Chris, thumbs up. I would just add that "ideally" you would have manually gone through all the links ahead of time and had the 301s in place prior to launch.    That way there is no downtime/confusion to Google on what they are supposed to do with these pages.  If you think about it you have 600 pages that are in limbo and so after a while Google will just say, well, I guess those pages are dead and start to crawl them less often and eventually drop them.

I would make it a priority to go through those pages and setup the new 301s ASAP.  Google will keep trying a old page for a while (few months) if it 404s or even if you have a 301.  It knows that mistakes happen.  So in the case of the 301, it will still crawl the old URL for a while even after it sees the 301 the first time, just to make sure that the 301 is really permanent.  You have a bit of a grace period so take advantage of it to get things cleaned up quickly.

2. use robots.txt vs the meta tags - robots.txt is preferred.

That is a completely valid question.   This is why setting up the separate GWT account for the dev.domain.ext vs www.domain.ext.   When you submit the removal request it will only be in the dev.domain.ext account.

The only thing you want to watch is that if you setup robots.txt in your dev environment you want to make sure that it does not get pushed out to your production server. That is the only gotcha as I see it.

Here is a Google documentation on how to use the GWT to remove a page/directory/site and then the interaction with robots.txt

http://googlewebmastercentral.blogspot.com/2010/03/url-removal-explained-part-i-urls.html

"In order for a directory or site-wide removal to be successful, the directory or site must be disallowed in the site's robots.txt file."

Side story.  I once had a subdomain that I needed to take out, but I could not modify the robots.txt file properly (long story).   So, we used the GWT tool and the meta noindex tag.  It still worked, but I think that would only be a backup approach to the one suggested by the documentation.

Usually, this would be true that you would need to use the noindex tag to get things out of the SERPs and need to leave the robots.txt "open" to the crawlers.  But when you are working with the remove URL tool in GWT,they rx that you then put the site in robots.txt to keep them out of it

The removal tool in GWT takes care of Google taking the URLs out and then the robots.txt keeps the bots from coming back.  Just a different sequence than if you were to use the noindex meta.

If you create the GWT account for the dev site and you submit for removal, GWT requires that you either a) have the site blocked in robots.tx or have a noindex meta tag on the pages. Otherwise they will just crawl you again later and you are back in the index.  See my post from earlier.

Short answer - no dev sites should be public to start with to anyone (let along Google et alia).  The simplest way is to put an htacess password on all your dev sites.  You can do a password per person in your company, or just one general one that everyone on the dev team shares.

If you do have a dev site in the Serps, the simplest way to get it out is to setup a GWT account for that subdomain and then e.g.  dev.yourdomain.ext  and then go into that account and request removal of all pages.  You just leave the form blank for the page to be removed and it takes out the whole site.  You then need a robots.txt on dev.yourdomain.ext (different from the www. version) that disallows all pages all crawlers - that or use the noindex meta tag on all page.

After about 1 month (or you see that the pages are all out of the serps), then I would put up a password on that entire site and be done with it.  Key point, dont put the password up until you let google try to spider and it sees the robots etc.

Also, if you have any other staging sites that are out there like  test.yourdomain.ext etc.  If they are not indexed, go ahead and put the password up on them to limit your exposure.

Public dev sites are the fastest way to get duplicate content into the index and to jack with the ranking of your current site.  It is key that all of them are locked down. If one of your developers say it is no big deal, call BS, it is a big deal and it can cause a big mess.

First and foremost when you finish all this - password protect your dev instances.  A url will leak out eventually and then this happens.  I know it is a PIA, but it is worth it.

To remove subdomains.  Go into GWT and register the subdomains as separate websites in GWT.  Create a robots.txt for each subdomain (not the one you mention, you need a robots that is specific to that subdomain that disallows all files.  If you cant do that, have your subdomains include a noindex meta tag on all pages.   You have to be careful with this as you do not want to push out your dev. robots.txt or the noindex meta tags to your production server, but it can be done.  Talk to your devs.    Then go into GWT and use the URL removal tool.  Just leave it blank and it will remove the whole site.

Poof.  Gone.  You can then watch the GWT accounts.  They will show errors for the dev site like "Severe health issues are found on your site - Some important page has been removed by request."  This is a good error as it confirms that that subdomain is removed.

We actually used this not on a dev site but on our www1 server that was indexed.  We use a load balancer with multiple copies of the site.  www1 was completing with www.   Using this above did the trick.