Looks like your saddle could come a little forward on the rails. Also, don't lock your elbows; you're more likely to injure your arms/shoulders that way. Instead, keep them slightly bent, elbows not sticking out, shoulders down and relaxed. Work on your core muscles so this position can become more comfortable. As for the stem, I'd go with an 80-90mm zero or maybe +5-10 deg stem.