Is formatting possible with the Google Data API?

Nope. There are two distinct API controls for Google Spreadsheets: the JavaScript-based one through Google App Scripts (the one you see from inside spreadsheets), and the server-based Google Data API (or gdata for short). The gdata API doesn’t provide for spreadsheet formatting. They say it’s a philosophical split between the two groups: front-end vs. back-end work, with the presumption that prettying up a spreadsheet shouldn’t be in the domain of a “data” API. They’re dead-wrong, because without formatting ability, you can’t start spreadsheets from scratch because they will look like shit, and you are forever resigned to the world of creating “template” files before-hand that you always have to maintain and copy to get formatting—which creates more surface-area for maintenance and more dependencies. Eventually, the gdata team will come around to realizing formatting belongs there.