行ってください è una forma educata di imperativo. 行って！ può essere un imperativo perché è una forma abbreviata di 行って・ください o 行って・くれ, una forma in cui ください/くれ, viene omesso. Ma 行って・くれて／くださって non può essere un imperativo perché non esiste forma ridondanta come くれて・くれ/ください。

ありがとうございました！本当に面白かったです。

I'm completely agreed with Ueda's answer. When you use してくれて for asking, it should be してくれたら, たら means assumptive things. Like, 手伝ってくれたらありがたい I would appreciate if you could help me./～してくれたら嬉しい。 But this one is not really the general way of saying. I guess it's because of the length. It's too much/long for normal asking we think. But we do use it when we want to be really humble. In the Japanese language, we think the longer the politer. I recommend using してくれますか, this one is asking is it possible for you to do or not, is it ok or not with you compared with ください which is an asking people to do. There're other grades of asking expression about politeness though this one is the most standard one.

My pleasure.

Thank you very much! It's actually a form I only encountered a couple of times in an anime, so I figured it wasn't real japanese :D