I'm looking for some resource that can help me decide what OpenGL version my game needs at minimum, and what features to support through extensions. Ideally, a table of the following format:

               1.0   1.1   1.2   1.2.1   1.3   ...
multitexture   -     ARB   ARB   core    core
texture_float  -     EXT   EXT   ARB     ARB
...

(Not sure about the values I put in, but you get the idea.)

The extension specs themselves, at opengl.org, list the minimum OpenGL version they need, so that part is easy. However, many extensions have been accepted and became core standard in subsequent OpenGL versions, but it is very hard to find when that happened. The only way I could find is to compare the full OpenGL standards document for each version.

On a related note, I would also very much like to know which extensions/features are supported by which hardware, to help me decide what features I can safely use in my game, and which ones I need to make optional. For example, a big honkin' table like this:

              MAX_TEXTURE_IMAGE_UNITS  MAX_VERTEX_TEXTURE_IMAGE_UNITS ...
GeForce 6xxx   8                        4
GeForce 7xxx  16                        8
ATi x300       8                        4
...

(Again, I'm making the values up.) The table could list hardware limitations from glGet but also support for particular extensions, and limitations of such extension support (e.g. what floating-point texture formats are supported in hardware).

Any pointers to these or similar resources would be hugely appreciated!