Can your body the same amount c-vitaming from absorb calcium ascorbate and ascorbic acid? i have problems with my stomach.

Yes: Yes, buffered ascorbate (including calcium, magnesium and sodium ascorbate) is absorbed as well as ascorbic acid. The best-absorbed form of vitamin C is liposomal Vit. C. Lyposphreric C, which is sodium ascorbate mixed with phospholipids for enhanced absorption, is a product I often recommend. See http://www.livonlabs.com/cgi-bin/start.cgi/liposome-encapsulated/lypo-spheric-vitamin-c.html