1. For the resource that is produced by the top left corner of a civilization, it can be traded with a trading post for 1 coin instead of 2. But it doesn't count towards the effect of commerce cards in the second and third ages (ie, cards that gives you bonus coins/points for each brown/grey cards that you or your neighbours have).
This is correct. E.g., if Rhodes is to my left, I can buy the 1x ore it produces for 2 coins, just if it were a resource produced by a card, or for 1 coin if I have the West Trading Post.
However, I won't count that 1x ore for cards such as Vineyard, Worker's guild, etc. It's explicitly specified in the very last sentence of the Rules:
Last sentence of 7W Rules wrote:
Clarification: Resources produced by boards are NOT considered as cards (Vineyard, Bazar, Guilds, ...).