Modular cyberlimb plug ins are replacement specialized equipment or tools "clicked" into the UCCP. Now is this a limb with the equipment or tool integrated?
Example: I "click" in my Built in Medkit to my uccp joint on my left arm. Do I no longer have a left hand or do I have a left hand and a med-kit now?

Just the Medkit. You're not popping on a Swiss army cyberhand, you're popping on a specialized partial limb that contains a bunch of specialized tools and sensors, some of which may be on tiny electromechanical armatures. Typing is generally out.

yes. you have to replace the hand but it could still be really usefull i think. i like the flavor of it.

Actually I think my favorite use for this system is to have alternate lower arms when dealing w/ cyberware scanners.

While a lot of the specialty tools are pretty neat and in some cases maybe even worthwhile. It also allows you to change your capacity based cyberware on the fly w/o much hassle. Or for example... put a synthetic (non-obvious) lower arm and hand on, to make it less conspicious sticking out of your jacket.

EG: my normal street legal cyberarm... then my jumped up illegal one w/ questionable cyber/mods/augments. (possibly in some shielded compartment for later reattachment). (EG: cybergyro, 'R' arm augmentations, cyberweapons, etc).

Reminds me a bit of the old GI Joe Battle Android Trooper, with being able to switch out hands.

The arm laser is amazingly useful, actually. It's a laser gun you can start the game with and has 5 or 10 shots (IIRC), deals 5P damage, and is -1/2 AP.

Also, the Raptor Legs are amazing, look KEWL!, and still have enough room to fit some R6 Hydraulic Pumps.