Super-Newbie Question: Nighthawk X6 Antenna Orientations and Signal Footprint

Hi, all - I was gifted a second-hand Nighthawk X6 R8000 router. I've downloaded the user guide, et al, but can't find one piece of information. The manuals and the marketing materials show the antennas in two different positions - vertical or angled outward. Does the position of the antennas affect the signal footprint? Also, is the footprint uniform or is it lobed - that is, stronger in one direction than another?

The situation is this: I live in a very old house - like mid-19th century Victorian old. This causes two issues with Wi-Fi:

1 - Big, thick, plaster and lath walls - No cheesy wallboard here! And there are several of those big thick walls between office (router) and bedrooms (late-night surfing). My signal randomly drops in the back of the house using the modem/router from the cable company, while I have no dropouts when I'm surfing from the living room, with only one wall between router and device. 

2 - The router pretty much HAS to be in the office at the opposite end of the house from the bedrooms because, when the place was wired (some time in the dark ages) no one bothered to put electrical outlets in the entryway or hallway, because who'd need outlets THERE?!!? (And the office is also where the cable comes into the house,so there's that). So the router either HAS to be in the front corner of the building, OR I have to snake power and multiple ethernet cables around the baseboards and through the office door to get it centrally located and remove one wall from the equation. (The lack of outlets between here and there also means that a signal-booster/repeater isn't an option.)

I assume - and please correct me if I'm wrong - that the six antennas on the Nighthawk are arranged so that each pair (left-right-front, left-right-middle, and left-right-rear) serves one of the three Wi-Fi bands that the router supports. Will I get a stronger signal in the back of the house if the (assumed) paired antennas are perpendicular to that line to the bedrooms, or does the signal propagate uniformly and the orientation of the antennas is irrelevant?

Also, as I noted above, sometimes the antennas are shown in Netgear's materials as straight-up vertical and sometimes angled outward. Does the antenna angle have any effect on the signal propagation?

Please excuse the long-winded nature of this post - having used the cable company's bog-standard hardware for so long, I'm not used to having all these options to consider!

Thanks in advance for any advice on my problem or corrections to my woefully incomplete understanding of how these things work!