A patent would protect a technique, not a file format. (i.e like LZW compression, not the layout of the GIF file structure). An independent technique for generating the same would not be covered by the patent.
I'm not so sure. Although functional claims shouldn't issue, they regularly issue. And therefore the format specification (or more precisele any technique to produce such a format) may get a patent, of dubious validity but sure harm. If you have an "unpatented" format that can only be produced through patented processes (since the patent covers any process to generate it), you have an effectively patented format. I'm not sure of the details for GIF, but if the format specifies LZW compression, you can't have compresed GIF files (I think the GIF format allows for uncompressed files, but another frmat might not). You could use gzip instead, but that'd no longer be GIF.
On functional and non-technical claims, see http://swpat.ffii.org/analysis/invention/index.en.html
Instead of bothering to have the above arguement, you could have just fired up a webbrowser and spent a few seconds on google to turn up http://www.wvware.com/.
I haven't found an spec there, I've found:
The MS Office file formats (Word, Excel, Powerpoint, Office Binder and Office Drawing) were all made freely available from the MS msdn website in 1998. Since then they have been removed, but MS made cd's available of their website to developers that registered to receive them. These cd's are commonly available. The particular cd that the specifications were made available on is the July 1998 edition. CD Number 2 of the three part set. The specs that were made available were the office 97 spefications. Not the previous versions. The specs are quite hard to read, and often incomplete. Some fields are wrong, and some information is not fully correct, but theres nothing better available.