Cost on the 1/700 Carriers can vary from about $30-40 to 60 or 70 if there is extra stuff in the kits. The 1/350 scale is the pricy stuff as these can get into the $250-350 range and in some cases the etch accessories can can add another $30-40 up to double or triple this depending on just how much you want to do.
Yep, always on the MATT paint surface, then once it is right a light gloss coat to seal it in, more can be added to your liking after the matt clear coat is applied in the final stages.