4. Ask around and see if someone has an extra WiFi router. Put them on reasonably separated channels, and as much physical separation as you're willing to hardwire, and spread the load among them. Repeat as needed. I've seen three sitting on the same shelf without issue, but having at least a couple yards between them can't hurt.
Possible, but ugly. If he's buying a kit of 8 of them, it's probably cheaper to get a kit that includes the router.
This gets complicated.
Okay. There are 2 frequency ranges for 802.11 networks. 2.5Ghz and 5Ghz.
2.5Ghz has, at the same power, under laboratory conditions, a better ability to penetrate, and thus longer ranges. However, not only are there only 11 channels(legal) in the USA at this frequency, only 3 of them don't overlap. So if you're on channel 7 and somebody is on channel 6 or 8, they will be interfering with your network. Even 5 and 9, to a lesser extent.
Plus, "most" wireless networking equipment is operating on this band, as well as microwaves, baby monitors, wireless mice, bluetooth devices, and more. The frequency is
busy.
Meanwhile, at 5 Ghz, there are 28 channels(sorta, can be complicated). Better yet, they're non-overlapping. The only restriction is that there are radars operating in this range, but they'll only use 1 channel themselves, so the routers are programmed to change frequencies if they hear a radar. But that's likely only to cost you a few channels. So you're more likely to be able to find a channel that works. While 5Ghz doesn't penetrate as well, it does "bounce" better, so you're still likely to get signal, especially if you leave the door open. Multipath(multiple antennas) helps with this. The net result is that in real world testing, 5Ghz will often get you better speed AND range.
Finally, under the rules, you can turn up the power more on some of the channels, so if you have a reason and are willing to do the research....
802.11A is 5 Ghz, 54mbit, depreciated. Development on this protocol started first, which is why it is "A", but it took so much longer that B was released first.
802.11B - 2.4 Ghz, 11mbit, depreciated. Quickly developed cheap protocol. Apparently at the time 5GHz transmitters were expensive and couldn't be done in silicon, but had to be done with gallium or something, raising the expense.
802.11G - 2.4 Ghz, 54mbit, depreciated, but still common. Basically "A" ported to 2.4Ghz with stuff to play nice with "B".
802.11N - 2.4 OR 5 Ghz. What I have, though I'll note that many of my connections are still wired. A disturbing amount of hardware only capable of 2.4. A notable feature here is the ability to use TWICE the bandwidth - rather than 1 20 MHz channel, it can use 2, and instead of 1 antenna, it can use up to 4. With a single channel and antenna, it can reach 72mbit in normal environments, up to 150mbit if the band is relatively clear(no bluetooth, microwaves, or other networks around). With 4 antennas and 1 channel, 288 mbit. If it can use 2 channels, 40 MHz, and 4 antenna it can go up to 600 mbit. Note, if you're trying to do this with 2.4Ghz you need to have quite some property and be avoiding 2.4Ghz devices otherwise. Because, well, I have a good section of woods around my house, can't see the neighbors at all, and I can still pick up 4 networks other than my own...
Now, 600 mbit should do you. It also sounds more impressive than it is. That 600 mbit is simplex - shared between all devices. A 100mbit wired connection is duplex - 100mbit down, 100mbit up. And these days they're all switched, so every connection gets a dedicated 100mbit(or 1Gbit). So 8 wired cameras = 1.6Gbit of potential transfer, 800mbit down, 800mbit up, even though they'd never use it.
So a cheap wireless-n, single channel, with 72mbit might be enough for you. Anything fancy with 4 antennas should be sufficient, bandwidth wise, though I'll note that I can't "guarantee" - home construction, wires in the way, interference, other devices, quality of the devices all make a difference. Size of the home, placement of the router, etc...
802.11ac - 802.11n times two. 80Ghz channel usage. 8 channels. 1.2 Mbit maximum theoretical speed. But good luck finding cameras that support this yet, many are still G standard.
And I see you've replied dogmush.
Are your routers both physically wired and on different frequencies? Dual band implies N at least, there were some A/G routers that could do that, but not many. If they're wired and on different frequencies, then you should be good to go. If one is acting as a bridge or repeater, talking to the other wirelessly, that cuts your available bandwidth with that device in half.