SSDT on VS2013 for SQL Server 2012 I have Visual Studio 2013, and SQL Server 2012. From what I'm reading, it seems that the SSDT add-in for VS2013 only works for SQL Server 2014. Is that correct?

I've installed it, and I built a SSIS package that runs fine from Visual Studio. But when I attempt to import it to SQL Server, I get a generic 


  0xC0010014 "One or more error occurred...This occurs when CPackage::LoadFromXML fails...


My guess is the DTSX format isn't readable by SQL Server 2012.

Is there something I can do to make VS2013 save in SQL Server 2012 format, or another way to import my package to SQL Server? I'd rather not have to install VS2012 on this machine since I've already got 2013.
That is correct. Forward compatibility is guaranteed. Backwards compatibility does not exist*. Having 4 different BIDS/SSDT instances on a machine is a pain I've known all too well but there's not much you can do.

There are ways of constructing SSIS packages such that your solution can target whatever version of SQL Server will be hosting them but that's installing, purchasing and learning a separate product (Mist).