Andy Savage, your questions don't seem to have much to do with the original thread. You might want to make your own thread.
Which type are you asking about?
There's no Paizo-produced half-giant for players. There's no large variant of human either. There are stats for trox and for centaurs (both size large) but both of these are expected to be noticeably more powerful than humans, and shouldn't be played alongside normal races without some form of compensation to people playing those normal races.
I don't think there is any ban on multiclassing with Monk in Pathfinder except for certain things, such as Monks have to be Lawful, and Barbarians can't be, so being a Monk/Barbarian is a problem (though not an unsolvable one).
I advise against multiclassing with Unchained Monk. It is because I like to multiclass that I prefer Core Monks.
Core Monks have 3 Good Saves; Unchained Monks have only 2, and their Poor Save is Will, and that's the most important Save to have. I rate the Will Save as much more valuable than the Full BAB.
Core Monks get Still Mind at level 3, and Unchained Monks get it at level 4. Not only does Still Mind give you better Saves = good, Still Mind is a prerequisite for the Monastic Legacy Feat, which allows 1/2 your nonmonk levels to count as Monk levels for the purposes of your Unarmed Strike Damage. Still Mind is a prereq for other things I like, too, especially for multiclassing.
You cannot multiclass to have both normal and unchained versions of the same class - they effectively count as the same class for this purpose. Ie you cannot be a cleric, multiclassing into cleric.
No, you can't be a Core Monk/Unchained Monk! I did not catch that the OP was considering doing that!
You also can't be a Rogue/Ninja nor Cavalier/Samurai.
Thank you for your answers again sorry about miss posting out of subject but did figure out. Would anyone know if Scarab Sages faction is still a functioning faction. I signed up early May and had my first op game on June 16th. Local GM and Pathfinder society in Pittsburgh wasn't sure they were doing Scarab Sages faction anymore(not sure if it's over new edition or what not) but did earn faction points for that game. If Paioz disband or no longer uses a faction will points earned transfer to new faction or will lose what I earned.
Original and unchained are not separate classes or even archetypes--they're considered different versions of the same class. Being a monk/unchained monk would be like multiclassing a monk/monk.
For PFS-specific questions, try the PFS forum. The Rules Questions forum is for questions about the rules of Pathfinder RPG in general, so it'll be more difficult to get a good answer about Society rules here.