This has been up before, in a different thread -- maybe someone a little more computer savvy than I can post a reference to that thread.
In answer to what's your hand range, I happen to have very long fingers and can easily span a tenth. A twelfth? no hope! However, in my humble opinion that really isn't as important as it might seem: there are remarkably few places where it is really necessary to do that. What is necessary, however, in my view, is the flexibility of the fingers in between, and this is worth practicing stuff for. For example, it can be very useful indeed to be able to span an octave with 1-3, 1-4, or 1-5 as you choose. It can be downright handy to be able to easily play, for example, an octave with 1-4 (I'm looking at the right hand now), with, for example, 2 on the fifth, and then shift effortlessly (!) a whole tone up, with 1-5 on the octave and now 3 on the corresponding fifth. Or hold an octave with 1-5 -- say C to C' -- and play an intermediate figure alternating F and A wth 2 and 4 with a G with 3 -- or E and G with 2 and 4 and F with 3. And so on.
Exercises? Play the piano. In my view hand exercises, unless very carefully prescribed and thought out, are likely to more harm than good...