You're welcome! :-)

The word order sounds very strange. It might be right only if you're specifying, like :"It's time to go home for the girls. The boys must stay to clean up."

The common use.

If you say something like "Папе пора спать" it means dad is still awake and, in fact, is not even in bed.

If you omit the verb and state a destination (special case), like "Папе пора на работу" it means that dad is still not at work and, in fact, does not seem to have done anything to be at work. So he needs to get going.

Same here. If you mean that it is high time for someone to show up you do not say it like that—you rather say «Девочкам пора быть дома» or rephrase it to «Странно, что девочки ещё не дома» ("It's odd the girls are not home yet") or any other sentence that expresses your feelings good enough.

It is a noun used as an impersonal predicate word (the noun means "time" as in "a period of time or a suitable time for something"). Modern descriptions usually describe such predicates as a separate class: category of state words.

The noun itself is not particularly common. However, it is quite common in certain structures or derivative expressions:

• Dative + пора + infinitive ~ It is time to do something (as in the the sentence in the title)
• до сих пор ~ up until now, before now (note how both сей and пора are not common words this day—but the combination is)
• до тех пор, пока... ~ until (a compound prepositional phrase, literally "until the time when")
• с тех пор ~ since then
• порой ~ occasionally
• до поры до времени ~ for the time being, until some time in future.

English doesn't have a separate verb form for subjunctive. The only verb that has one is "To Be" and that form is "were". For all other verbs English can can express subjunctive using the infinitive or the past tense.

In this situation there is doubt whether the girls would agree they should go home and/or whether they would actually leave. "It's time the girls went home" therefore uses the past tense to express subjunctive. We know this because "is" is in the present while "went" is in the past, therefore you know "went" is demonstrating something other than just the simple past tense.

Another version of this should be: "It is time the girls go home"

Of course not.

The word order is strange like that. People may understand, but it doesn't sound natural.