He sounds like a wee smasher, you should count yourselves very lucky that you were The Chosen Ones! It's a shame that you couldn't get two, but it sounds like she would have been too timid for a house with DCs anyway. And fingers crossed his murmur sorts itself out
Right, advice time! Firstly, if you can, try to make your vets appointment so you can go on the way home from the shelter. The vet will check him over, give him his injections, worm him etc (all the nasty stuff!) and then you can take him home and get him settled in. It's not a big deal if you can't get an appointment at the right time, it's just a shame to yank him back out of the house when he's starting to get settled in, and it means he's only got one scary car journey. You won't need a catflap yet - he shouldn't be going out for a good few months (until he's a bit more street-wise and has been neutered - you don't want him becoming territorial and starting to spray). And you shouldn't put a collar on him because even the special cat ones can cause a hanging danger if they get caught (they're also masters of getting their legs stuck in them, and it might affect his hair growth and leave him with a baldy patch). So that's two things to cross off your list!
Bed-wise, just buy the biggest cat carrier you can find (to save you having to buy another when he's bigger) and put some soft fleece blankets in it. Primark do them for £1.50 each and my house is full of them - they're soft, cosy, wash very easily and dry quickly. Using the carrier as his bed will give him a safe little den to retreat to, and will make him less nervous when you need to take him anywhere in the car. Honestly, don't bother with any other beds until he's a bit older and has decided where he likes to sleep - we ended up with beds dotted all around the house, because we put one wherever we saw them snoozing! He'll be just as happy with a folded blanket, and will probably spend most of his time asleep in the most unsuitable place he can find.
For his toilet, get the biggest tray you can find that has a cover and a door (you can take the door off if he doesn't like it, but leave the hood on). Boys can be very messy pee monsters! Don't bother with those plastic tray liners that you can get, they always get ripped when they're scratching about. The best litter I've found is the Catsan clumping litter - it's got a very fine texture like sand which doesn't hurt their paws, and any wet areas clump together into a ball so they're really easy to scoop out. A bag lasts for ages because you only take out the dirty bits and the rest gets left behind, so it's very economical (even though other litters might seem cheaper, you have to use a lot more). There's also less smell because the tiny granuals coat the poo and form a barrier over it. Miles better than any of the gravel or paper litters I've tried in the past.
Do you know what he's being fed at the shelter? It's best to keep him on the same food initially to avoid upsetting his tummy, but if it's not a very good one you can slowly change it over to something better. My two get a bowl of Arden Grange dry food every morning (to eat throughout the day) and share a pouch of wet food at night. I'm ashamed to say their wet food of choice is Felix 'as good as it looks'. It's crap food, I know it's crap (only 4% meat and full of additives) but the damn cats won't eat anything else and shout the place down if I don't dish it up at 7pm prompt each night ! It's really just a night-time snack though rather than their main food, so I try not to dwell on it too much. But I wouldn't recommend anything like whiskers, felix or go-cat as a main food. If you can, get him onto something like Nature's Menu wet food which is 70% meat (and mine refuse to eat it - typical!). If he eats dry food, Origin is by far the best but very expensive. James Well Beloved is also good (expensive though), but stay away from the likes of Iams (lots of hype but it's not very good). Basically you're looking for the highest meat content, smallest ingredients list, and no artifical baddies. If the ingredients list is full of long words you don't recognise, steer clear. I've been very pleased with the Arden Grange and the cats really enjoy it. They only use human-grade free range meat, don't use any artifical additives or preservatives (not even in their raw ingredients) and all their foods contain cranberry for urinary tract health, prebiotics for gut health, taurine for general health, and glucosamine and chondroitin for healthy joints. I get a breeder bag from Berriewoods Wholesale, they're by far the cheapest I've found and a bag will last you months and months.
You must be so excited, have you thought of any names yet?