Yes, to both. You can request rocks, even flux rocks (they're not terribly expensive, but you also don't tend to get many of them because they're heavy). You can also buy all the steel junk and mark it for melting, and you can eventually get steel bars out of that. However, if you do that, only allow one smelter to melt objects. This is because melting something results in fractions of a bar being left in the smelter. They don't actually show up anywhere, but it is tracked. So if you melt enough junk for 3/4 of a bar each in 12 smelters, you have no bars of reclaimed steel. If you did it in just one smelter, you'd have 9 bars of reclaimed steel.
As for finding a good embark site... latest version family has an absolutely absurd amount of mineral wealth. I used to embark on 5x5 flux layer sites and got maybe 3 veins of coal. I just embarked on a 2x2 flux layer site, and have found at least 3 veins of each type of coal on my flux layers. I have a 20x10 stockpile just for coke, and it's full, and that's only from 2 zlevels worth of coal!
The hardest part of finding a 'good' embark is finding one without aquifers. So I kinda ... cheat and remove the aquifer tags from all the soil types in the raw. No more problem

It's now just a matter of poking around to find something I like (heavily forested, flux layer).