Re: Info on 1212 needed
The pin spacing for all TSSOP/MSOP packages is 0.025" (40 pins per inch), or 0.635mm.
There's no single datasheet that lists all chip footprints (at least not one that doesn't cost a few hundred dollars from the standards organizations), but any chip in a TSSOP/MSOP package should have a measured drawing toward the end.
In a pinch, ON Semiconductor and NXP have good dimensional information in their datasheets. TI provides good drawings, but they make up their own package names, and it takes about fifteen minutes of reading cross-references to find out if you have the right one.
I think the library used to make the breakouts is part of the Adafruit Eagle library, but here's a copy in case it isn't: