No.

No.

No. For patents, whoever registers first owns the idea. If you independently came up with it, it doesn't matter. And the patent office isn't really qualified to do this research, which makes the situation much worse. For LZW (the basis of GIF), the patent office actually gave the same patent twice to two different companies (IBM and Unisys)! In theory, if it's publicly known it can't be patented later by someone else, but court costs make that only theoretical. Because the costs are so large, only companies can practically participate in a patent court; even if you're right, you'll lose (and create a court decision making future losses more likely), because individuals cannot afford the fees to make it through a patent court case.