15% is fine IMO
you can use the same syringe for both compounds and pin them at the same time. do not reuse the syringe AT ALL. always use a fresh sterile syringe and pin. as for preloading and storing, I personally do not like the idea of that
look into prolactin antagonists such as caber, bromo, prami... some say b6 pills do the trick. i recommend you having something on hand. i personally use caber and love it! ill post a link to that too, good read
adex on cycle should help with bloating if you opt to run that. are you gyno prone at all?
http://forums.steroid.com/showthread.php?t=398794
^HCG info
http://forums.steroid.com/showthread.php?t=356499
^cabergoline info