Is it Legal...to have a WILL read (probate) will all the persons NOT present?

Technically nobody has to be present. Probating a will is just a transfer of ownership of property. As long as the right people wind up with the right stuff and you dont withhold that information or property from them, its fine. And there are other catches too. My mom died and left everything to me, my sister and my dad to be split 3 ways. With big things like cars and houses, the titles dont actually change names. In order for us to dispose of or sell the property we all have to sign the papers. Probating, for us, meant that in the eyes of the law our three signatures now make her signature. I hope that makes sense!

Probate is a legal action, done in court, to transfer the assets of the estate. The "reading of the will" is a Hollywood fiction from the movies. There is really no "reading of the will" per se. If a person can't be at the court hearing, that doesn't stop the hearing. Hearings are done at the convenience of the Court, not the beneficiaries or family members. That is what they (the beneficiaries) have lawyers for.

Yes, once a reasonable attempt has been made to contact all persons involved, the will can be read without all persons attending.

Yes, as some may be dead, or indisposed.

yes. In your time of death you should be granted a simple request as that. =D

Yes. If they are not able to attend, it is their problem.