Poochie is definitely in heaven.
I am so disappointed to learn the Kingdom of Heaven is that kind of place.
Let’s smoke cigarettes in Heaven.
This is heaven country. Where is that? Probably just in heaven (or if you want to be fancy, the kingdom of heaven).
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well. The 国 is changed to the reading ごく, though because of rendaku. Even heaven changes a little bit.