Redstar, I'm relatively new to security cameras and NVR's, but I otherwise have a good technical background so I'd be happy to share with you what I've been learning over the past year or so. I've been dabbling around with 3 different NVR's and 4 different cameras.
Incidentally, you can consider a switch to be something like a roundabout on a road intersection. Data comes into a switch by various ports/routes, and then due to a little magic, it all exits by one single route. Each camera feeds the roundabout (switch) from a different street (wire), and the roundabout only has one exit point, which sends the video information in the direction of your monitor screen somehow.
For comparison purposes, where a switch can be loosely compared to a roundabout, an NVR can be loosely compared to a roundabout plus a huge parking garage plus a movie theater, all under one roof. That's not quite how it is, but you get the idea.
You already have 2 wired IP cameras and one possible NVR in mind. (Advice: For ease of connection and troubleshooting, always try to use the same brand of camera and NVR.)
How would you wish to view the video that is output by those cameras? If you just want to use a computer for that, then (using standard ethernet cable) connect the camera outputs to a POE switch, and then connect that switch's output to an internet-connected network router that's also accessed by the computer. In that case you'd need to buy software for the computer, such as
Blue Iris. It's not cheap, and especially after you install more cameras than you currently have in mind. If you go the 'computer' route, you'll be better off if you have a dedicated computer which just watches those cameras, and nothing else. That way you won't be busy using another program (Word, Photoshop, whatever) and it has a glitch at the wrong time, which then spills over into Blue Iris, etc. and there goes that video of an intruder in your back yard.
Since your cameras have the Power-Over-Ethernet (POE) feature, then each individual camera is set up to simultaneously receive their DC power, and send their video data back, over a single ethernet cable. In that case the POE switch which each camera wire connects to must have the necessary internal POE connections which allow it to receive video and also to send DC power over that ethernet wire. (Switches come with different port options, for example 4 ports, 8 ports, 16 ports, etc. The more ports a POE switch has, the bigger its DC power supply has to be, to be able to supply 5+ watts of 12-volt DC power to each camera.)
POE is a relatively new feature, by the way, so although some IP cameras still have two wires (video and power) sticking out of them, a simple little adapter can hook both wires up to one ethernet cable which thereafter makes it a POE cable. (You also don't need a POE switch on the other end, if you purchase some add-on POE adapters which get their DC from an AC adapter, but for simplicity's sake I'll just ignore that feature.)
If you want to avoid using a computer, and get a dedicated NVR with which to record and view the output from the cameras, make sure you get one that has enough POE ports. I have an LTS8708 NVR, and while it indeed has an internal POE switch, only 4 of it's 8 input ports/connectors are POE. So, I purchased a 4-port POE switch (around $30-$40) to expand my POE input capability up to 8 POE ports. The output side of my 4-port switch is connected to one of the NVR's non-POE input ports. Note that while the INPUT (camera side) of a POE switch must have the POE feature built in, the output (exit to your internet router) port is not POE. POE is only where DC power is piggybacking on an ethernet cable.
In summary, from what experiments I've been doing, you wouldn't be making a mistake by getting those 2 cameras plus that NVR. You'll also need a separate mouse, and monitor screen, but good used monitors are cheap. For example, I just today bought 2 Dell monitors for $20.