no
No it is not.
Playtime
Yes, "dateline" is a compound word made up of the words "date" and "line."
A sentence with a compound word is, He was excited about signing up to play football.
playground
The word is playground.
Yes it is. Play and ground is a word and it has a meaning
horseplay foreplay
Omg it's the woods
One such word is airfare.
No, building is not a compound word.