When you wildshape into an elemental, can you still use a weapon if desired? (Maul of the Titans or some other large weapon)
It's my understanding that the answer is 'yes,' provided you set the weapon down, wildshape, and then pick the weapon back up. If you wildshape while holding on to it, it will meld into your form.
No it depends on the DM. Polymorph specifically calls out that if the new form can wear and use your gear then your gear doesn't meld. So if your DM rules that elemental form can use weapons then your weapon stay and will automatically resize to your new size. However, if he rules the opposite, your gear will meld.
Yes Wildshape is a polymorph effect.
That's not the answer that I was browbeaten with by the Paizo rules forums when I asked a year ago.