This is a complex question. You would need to remove the feaure from the import before you imported it.
HEre is a PowerShell script which will remove features in bulk
http://get-spscripts.com/2010/08/bulk-deactivate-feature-and-remove-farm.html
You can do almost anyting with code I think if I were you, I would be looking for one of the 3rd part apps from Quest or another vendor.
Here is a blog post on migration from Joel Olsen look this over and see what you think.
http://www.sharepointjoel.com/Lists/Posts/Post.aspx?ID=337
Good luck,
Gary
blog www.sharepoint2010now.com
Gary Newman MCSE, MCT, CCNA MCDBA, MCAD, MCSA MCTS SharePoint 2007 Dev & Admin MCPD SharePoint 2010 Development Blog www.sharepoint2010now.com
