I used to be a racer so i know my wax and base repair stuff.  Your core shots you should probably use an epoxy that is made for the cold and fill it up almost all the way, then drip p-tex over it and scrape it off about 3-5 min. after you drip it so it's still kinda warm.  As for wax, i use swix ciera nova.  For cheap and effective stuff use their CH (hydrocarbon) waxes, if you have money to burn i'd suggest investing in some LF (low flouro) wax from them.  Make sure you use a wax iron, not a clothes iron because different waxes are meant to melt at different temperatures and in a clothes iron, wax gets stuck in the holes and burns.  Wax irons can be pretty expensive (50-300 dollars) but if you use it a lot, its worth it to shell out for the basic swix one.  The helpful part about using swix waxes and wax irons is that there is a setting for each number swix wax right on the iron(the number corresponds to the snow temp it should be used with).
     Anyways, i hope that'll help someone.  PM me if you want any more details or advice.
           -Andrew