I checked both of those links. The first appears to be incorrectly written, as it says the plural third person is vosotros, where vosotros is actually the plural second person (informal), that is, the plural form of t. I'm not sure I trust that page.

You're referencing Wikipedia! I thought you were on my Wiki-haters list....

There may be some confusion and/or controversy regarding the "third person" label. In Spanish, the forms for the third person are the same as those for the second person formal (Usted and Ustedes). I don't believe the imperative forms are truly third person, but the forms are used for Usted and Ustedes. Since the labels are debatable, I'll leave it at you pick yours and I'll pick mine.

Regarding Viva el rey!, I believe it is a shortening of Que viva el rey!, which can be translated "That the king (should) live" but is generally "Long live the king". This would be the subjunctive.

On a personal note, zmjezhd, my intent was to be humorous about the corrections, with a little added jubilation (I rarely get to be the "expert"), which should indicate to you that I rarely see mistakes from you, and that your knowledge base is deep and awe-inspiring. I did not intend any disrespect, so if you felt that, I do apologize, as I did not wish to even imply any such thing! :0)