Is it possible to say, "Não é a hora de comer."?
Yep, thats correct too
nao é tempo comer?
No, you have to add "para" or "de" (não é tempo para comer) Even though, "hora" makes more sense in this context.
Shouldn't it be correct to say "não esta na hora de comer"?
So as to make sure I get this right:
You can say "Não está na hora de comer" and "Não é hora de comer", but "na" and "a" can't be omitted.
So with "estar", one needs to use "na" and with "ser" there is no need for a preposition between the verb and "hora"?
Why is it "de comer" and not "a comer"?
I think it relates to the act of taking food, or eating it rather than just 'the' food.