Hello there
For 1: If you want to stay true to the rules then no, but that isn’t always fun is it? Then again you can juggle the rules a little since it doesn’t actually state other creatures CANT do it, the gist of the exception being: “A creature able to engage more than one PC at once can within one and the same Round of Limelights act upon more than just one PC’s Limelight”, the keyword being An Able Creature
Then there’s the bigger rules that are the Rule of Cool and Rule of Common Sense. Does it make sense that your big ape can engage several PCs at once due to his high agility, multiple arms and overall badassery? Does it LOOK COOL? Maybe a bit of narrative power and scenario description helps picturing this, for example the apedude flings from side to side through vines and platforms while engaging the PCs that are in different areas.
I usually use the limelight-per-pc to portray boss-like NPCs that could cinematographically engage the PCs in cool fashion. While your basic elite gladiator or bandit warlord might not fit the criteria, think of magical alien-like beasts that can fling around & walk the ceiling, werewolves, the Naga and the 6(!)-armed Kali (from sinbad’s), a medusa, a flying gargoyle or some sort of Dracula-like ancient being that is simply too experienced and supernaturally fast, even perhaps with some sort of teleport or precognition ability.
Anyway, i’d say go for it if you are going for more of a “boss” type of fight or something more cinematic or just stick with the regular rules but perhaps give him an extra MP or two or some specific asset due to his multiple-arms, if you are so inclined.
For 2: If the ape use his fists for punching, then use the punches and kicks stats, if he uses his claws use claws stats, seems like a no-brainer.
Another thing you can do that isn’t in the core rules is giving assets to your more crafted NPCs. For example, your apedude could have the Brawler asset for some unarmed badassery. Another thing to note is perhaps to not use michael’s rule-addon regarding unarmed combat (that is, multiplying unarmed successes for 0,66) in regard to large, huge or powerful creatures. Other than that, I figure this creature will have a high amount of brawn (9 or perhaps even 10) which is some serious damage output and damage reduction, damage halving rules notwithstanding.