it is not "刘要"，it is "就要" . there are not many differences between them ,they both mean something will be happend soon. but "就要" is much more closer to the thing which will be happened than "快要" ,for instance: “我快要上学了”means i will go to school soon , assume that there is a guy in his vacation , when the vacation has past 2/3 , he can speak like this. "我就要上学了" mean i will go to school soon . assume that there is a guy in his vacation , and one or two days before the vacation is overed , he can speak like this. "刚" is an adverb , ”刚才“is an adjective. for instance ”我刚吃饭“ , means : i am having my dinner now , and i had began to have my dinner just a few minutes ago. "我刚才在吃饭", means : i have finished my dinner now , and the last thing i had done was having my dinner. if you and a guy both on the top of a building , and he want to go down and do something , then you can sak him "你下去干什么？",means :why are you going down the building,what are you going to do ? if you are at the first floor and the guy is on the top of the building , then you can say "你下来干什么？" "回来"and "回去" are somothing like "下去"and "下来" ，like "我回来了." ,means you have come back from somewhere.”我回去了“means you will go or have gone back to somewhere ,and the place both you and the man who you are talking to know there.

“回来”means come here “回去”means come there