がん・ぎゃー・がね・がや
These are very hard to explain.
they can be used to add politness but:
i have added them least to most polite in titles of this post, so 'gan' used in when you want to sound colloquial and polite (only with friends and family)
gyaa, is often used as nicer sounding gan, or just to to say gaya easier
gane, is girly, or very polite
gaya is standard
gane and gan have more of a meaning of -jan
gaya and gyaa also can mean `jan, and aside from what ive already posted in other post it is just used emphasize