OK, so how about the power. is 300W enough to drive two 250W subs? Or at
least for the time being. I just don't want the subs to distort because of
too little power.

Speakers can't distort from too little power. The only way you can cause
distortion from too little power is if you drive the amp into clipping in
order to get it louder than it can cleanly play. Having two subs instead of
one will help prevent that as the total sensitivity of the system is
increased due to increased cone area.

All else being equal of course.