Studies have shown GHRP-2/6 raises prolactin levels but usually this is with higher doses. Hexarelin is the worst for this and in nearly all studies prolactin was elevated. Cortisol can also be raised by the 3 I just listed but this is much rarer. Ipamorelin shouldn't have any effect on prolactin or cortisol. Some people may be extra sensitive to prolactin sides or past/current aas use put their levels in the danger zone and the peps just took them over.
There are many factors that come into play. Most importantly is the management of aromatization when on cycle. A higher estrogenic environment will only increase the chances of prolactin gyno. So when you have guys running the likes of test and dbol etc you should always run an AI such as exemestane. Now if you add in some of the peps I mentioned above you are best using a dopamine agonist to lower prolactin. I would recommend cabergoline or pramipexole.
Only blood work will let you know your exact levels of estrogen and progesterone etc.
Waybigger yes letrozole will help lower water retention. It will also help with possible aromatization. I personally don't like to use letro as an on cycle AI and much prefer aromasin or arimidex. If you ever develop estrogenic gyno then tamoxifen is the best thing you can use to get rid of it. If you are running aas than the AI too to stop it from coming back. JJ yeah letro will help dry you out fast especially when using aas. That's what I would recommend it for... only issue is it can mess with your sex drive and joints severely at higher doses... but it will help you get ripped