Cisco Switching/Routing :: SG200-50P And PoE Configuration

I currently work in the IT field part-time as a end-user support technician while I am finishing my Bachelor's Degree in Network Administration.  I'm not completely new to networking at this point, but I am by no means a master of it either.  The basics of small networks (less than 10 PCs) and the lower-end of small business grade Cisco equipment are not unfamiliar to me.  Up until this point however, I have had very little experience with any higher-end Cisco networking equipment.
 
Now on to the questions, which may seem like the answers should be obvious, but let's face it, I do not have the resources to own much equipment myself at this time for experimentation purposes, nor does the school I am attending have a lot of financial resources to provide us with recent hardware to learn on.  What I want to know are a few things about PoE as implemented on Cisco devices, specifically the SG200-50P small business series switch.  According to the technical documentation, the switch supports PoE on 24 of its 48 ports, specifically 1 - 12 and 24 - 36; simple enough.  The switch is currently installed in an office that has less than 24 connected devices, but that is currently expanding.  None of the PoE ports are utilized as of yet, but going forward, there will be more than 24 connected devices.  Will another switch need to be installed if the additional connected devices (PCs and printers) are not using PoE, or is the PoE an auto-sensing feature that will simply remain disabled if a device that does not require power over the network cable is connected?  Is there some setting that needs to be changed through the management interface to keep devices that should not be drawing power from doing so?
 
There will likely be some additional questions generated by my inquiry, and I fully understand if these are completely novice questions, but I admittedly do not know the answer.  When I Googled it, I was greeted by a few hundred thousand results, the first dozen or so pages of results all being for places to purchase this particular type of switch, so I thought I would try my luck on the forums of the place that made it.