any website that sells snowboards is a good site to buy 139 cm snowboards. It's more of the question whether that particular shop has any boards of that length in stock. try: www.rei.com www.backcountry.com
Alpine is far superior to pioneer, as far as im concerned not including the high end stuff alpine is the shit!. i own a new alpine head unit and it sounds awesome has good features and it cranks way louder than my buddys pioneer.
No. Assuming you mean alpine (downhill) skis, you should take them to a ski shop (or to the repair place at your ski mountain) and for $10 to $20 they'll apply a hot wax. Also make sure they sharpen the edges too, as they rust up and/or dull up depen...