Concerning this: Can the POE travel through the Punch Down? Any downside to this?
Yes the POE can travel though the punch down connections.
The downside, each connection increases resistance and voltage loss. Will that matter? How long is the cable run between cameras and the rack with the POE power source?
The longer it is, the better chance of your POE cams having problems. Specially if the cams have built in IR. IR can take a lot of power to run.
You can always leave a loop of cable to give you some extra slack. If your cams experience issues related to low voltage, try going direct.
Be sure your POE source is strong and has a good power supply. I like to use a POE switch that has a lot more powered connections then I will actually need, this gives you some power "overhead" so your not operating at max watts the power supply can produce. Example, you have 4 POE cams and you buy a cheap 4 port POE switch.
Then you experience power related problems with your cams and wonder what is wrong cause after all, you did get a 4 port switch so it should work right? Well, yes and no.
If I were running 4 cams, I would get a 8 port or 16 port POE switch so you have a power supply with "headroom" and room to ad more cams later as there is no such thing as enough cams. I myself am looking at that very situation right now, I want to ad another cam to cover a blind spot in my backyard. I have enough power, I think, as it wont be a super long cable run and I have plenty of extra ports on my POE switch. Just have to buy the cam, run the cable, plug it in and viola, I hope. Problem, it is 10 degrees outside. Kinda puts a damper of my enthusiasm for being outside running new cable and hanging a new cam. Probably wait til spring to get that cam added.
If you buy a rack to keep everything in be sure to consider cooling requirements. If it is totally enclosed, make plans and leave room for fans mounts to the inside top of the rack that exhaust air out holes in the top, or the top rear. Use super large, low speed case fans.
I have a few larger server cases and they have really big fans on the tops and sides but they are quite because they turn slow but move a lot of air. If I were going to use an enclosed rack, I would plan on the top 4 inches being open, then I would mount as many of these fans that I could with holes cut in the top.
If that would not work out I would make a false top via adding a shelf 4 inched from the top inside, mount the fans on that and leave the top rear open so the air would flow out that opening. How you do it depends on what is visible and what you want etc. Make sure to use industry standard fans so 5 yrs from now you can replace them easily.
If you use 4 fans, run them from 2 different power supplies, place LED lights inside run by the same power that runs the fans so you can easily see if a power supply dumps, and/or run some relays with a buzzer that is wired so the power keeps the buzzer from sounding, if a power supply goes out the buzzer sounds. With the 2 separate power supplies, you got a much better chance of only 1 power supply going out at one time. In an enclosed rack, everything will fry if your cooling system goes out, plan so it don't with plenty of fans and power supplies.
Save the very bottom of your rack for one of more UPS power backups systems. I suggest running 2 larger ones. You can find some good deals on new ones on ebay. Plan on new batteries for these every 2 to 5 yrs. Just because it is a rack does not mean you must run rack mounted UPS systems. You can easily use the larger rectangular brick looking models if you leave room.
Do keep these heavy UPS buggers on the bottom as if you don't, your rack could become a lot more easy to tip over. Do run some anchors from the wall to help hold it in place, specially if you have kids. Kids get into everything and you don't want a heavy rack falling over because junior decided to open it and climb up the steps (computers) inside. This includes grand kids.
Hope this stuff is of help to you.
Robert