Your clarification means a lot -- "baked" potato in the U.S. tends to be a whole potato cooked on its own, where the insides become fluffy and creamy, and is done with larger starchy white potatoes, or sweet potatoes work well, too.
Roasted potatoes, on the other hand, tends to be (in the U.S.) be smaller "new" potatoes, waxy potatoes, or even larger starchy potatoes cut up (eg, 'oven fries').
The starchy potatoes only really hold up well when roasting if it's very high heat or a short amount of time -- if you're going to be cooking them with the roast as there's going to be moisture in there, I'd go for a waxy potato (eg, Red Bliss).
As for the browning -- probably coat them well with oil, and if they're not brown enough for your liking when you pull the roast, as you're going to have to rest it anyway, drain the meat juices, crank the oven up to somewhere around 450F (230C) and leave the potatoes in for a few extra minutes.
ps. yes, I know a sweet potato isn't a potato. And I also tend to use Yukon Gold for just about everything, as it makes great baked potatoes, and roasted potatoes (although, not sure how well with a roast at the same time) and they're good in pot roast and stews if you don't add them too early.
Salt serves two primary purposes in baking:
- To regulate yeast
- Salt kills yeast. The addition of salt to a yeast leavened dough prevents the little beasties from growing completely out of control.
- To enhance and mask specific flavors
- Salt is almost a universal flavor enhancer. Virtually anything that tastes good, will taste better with salt. What typically comes as a surprise to people is that this holds true with sweet things too, particularly chocolate. The addition of even a tiny bit of salt can make a sweet dish significantly sweeter. It also serves to mask the taste of raw flour.
Update
Also according to Progressive Baker salt affects the strength and shelf life of baked goods.
Best Answer
This is what America's Test Kitchen (sorry, paywalled) has to say about it:
I have found that salt roasting potatoes makes the skin crispy, without it getting hard. Like the above says, the potato itself seems fluffier. The way the salt seasons the potato is particularly nice as well. Incidentally, you can reuse the salt over and over again, so it's not as wasteful as it might seem when you first consider the method. You'll want to keep separate salt for things like this, though, since it picks up potato flakes and discolors a bit.
EDIT The ATK method calls for covering the 9X13 baking dish (for 4 potatoes and 2 1/2 cups of salt) tightly with aluminum foil and roasting at 450F (232C) for 1 1/4 hours. Remove foil, brush potatoes with oil, raise oven temp to 500F (260C) and continue roasting for 10-20 minutes, until potatoes are tender when pierced with a knife and the skins are glossy.