Learn Farsi: الان ساعت یازده شب است.

No, Farsi doesn't use AM or PM. Instead, you add the part of the day after the number. In this sentence, shab (night) is used to show that it is 11 PM. If it were 11 AM, you would say sobh (morning).

Why is there an 'e' sound connecting yâzdah (eleven) and shab (night) when this is spoken?

That is the ezafe vowel. It acts like a little glue linking a word to its description or showing possession. When telling time, you use it to connect the number to the part of the day, making it yâzdah-e shab (eleven of the night).

Do I always have to use the word sâ'at before the number?

Yes, when telling the time in Farsi, you generally put sâ'at (which means clock or hour) right before the number. You are literally saying 'clock eleven' to mean 'eleven o'clock'.

Why is alân (now) placed at the very beginning of the sentence?

In Farsi, time words like alân (now/right now) are typically placed at the very beginning of the sentence. The verb, which is ast (is) in this sentence, always waits until the very end.