Regarding placing the hive(s) - you want the sun to get to it (if there is any) at some point in winter --- so don't put it close under the north side of a hedge!
Ideally, you'd like as much sun as possible - early morning summer sun gets the day started early ... while also having a bit of shelter from the coldest winds.
But you also want to be encouraging your bees UP, above head height, as soon after leaving the hive as possible. Trellis covered with fruit-protection netting can do that job if you need to "fence them off" somewhat to permit other uses of garden space (or to get them up before overflying a neighbour or a path, or whatever. I'd suggest that you could, if needs be, get off with just a couple of metres in front of the hive.
You need a "Plan B". If the bees cause problems or nuisance, temporarily or otherwise, you do need somewhere that you could, if you had to, shift them to. Maybe even an association apiary.
Your local association should provide you with a swarm at cost (travel, etc?) sometime next summer. Its the cheapest way, short of catching your own swarm! (A friendly local member might give you an old frame or two in the spring to help 'bait' your hive(s) to attract a swarm to move in.
Buying bees now means a lot of fast learning about the business of getting them through the winter.
Buying bees early in the spring, you would pay a bit of a premium for the anticipated productivity in the season just starting, and for the work that someone else has done getting them through the winter.
A swarm is good to learn on.
Running two colonies gets you a full set of your own spare parts (bees) in case of malign fate or beginners mistake. Otherwise you are back to begging for help.
So for two colonies, you'd need two hives?
Err no, nearer four actually!
You need spare kit for prevention of (real) swarms by performing an 'artificial swarm' - artfully dividing the colony yourself. (You can recombine later)
Implicit in the above is that ALL the kit is interoperable. You need to be able to interchange frames and boxes (otherwise an artificial swarm gets horrible).
So,
"a second hive to compare" needs to at the very least be taking the same frames!
So a WBC could just about go alongside a national (but you'll find the different box sizes quickly gets infuriating), so I'd suggest a poly national alongside a wooden one --- IF you insist on having two that aren't exactly the same. Standard-compliant hives from different sources/companies OUGHT to vary only in the quality of materials and workmanship, but do beware of those that 'improve' on standards by changing them. Nationals with top-beespace are a horrible but subtle problem when you also have a standard one!
