1) Talk to Wallingford Bicycles. For one thing, they've got a 6-month guarantee on the Brooks saddles, so if for some reason it's just not working, you can return it. For another thing, they were happy to talk to me via email when I first went Brooks saddle hunting, and answered some of my questions.
Brooks | wallbike.com
2) This is the company:
BROOKS ENGLAND LTD. | Leather Saddles, Cycle Bags, Etc. ... there you can browse the full range of saddles and other Brooks products.
3) Yes, they can last a long time. They may require a little bit of extra care, but it's certainly not onerous.
4) Yes, you can ride them without padded shorts ... but it may take a few months before you get to that point. I had about 4000 km on mine before I started riding around in a bathing suit and beach shorts up in Queensland.
5) When you get the saddle, it will be hard. Rock hard. You'll have feelings of misgiving. Maybe you made a mistake. You can rub it down with proofide if you want, but do not go crazy with the various "softening" techniques you may encounter and whatever you do, do not adjust the tensioning bolt in the nose of the saddle.
Your saddle should never become soft. That is not the goal. It will always remain a hard saddle. But it should conform to your sitbones over the weeks and months.
Install the saddle and be sure to tip the nose up. How much up will depend on you and may take a few rides to sort out.
The first time you ride the saddle, it will be slippery. You'll feel like you're going to slide off the thing. That's normal, but should go away in a week or two.
After a few weeks, you should start to notice slight scuff marks where your sitbones go. A few weeks later, those scuff marks will start to appear sort of like very small divots. And then you're well on your way to breaking the saddle in.