Elves try to be self-sufficient, making their own personal weapons and armour. They also happen to favour swords. These are mutually exclusive.

I don't get it. You're saying they couldn't possibly find iron by themselves?
Raw materials aren't really the issue (it is possible to mine in a forest, the real question is whether or not the elves want to) -- the problem lies in the fact that swords are very hard to make. Note that there are very few elves who can cast fabricate.

Someone who 'dabbles' in craftsmanship might be able to decorate a blade, or even help someone who does know what they are doing, but the bottom line is that swords were expensive for a reason.

What's wrong with their physique? They're just as strong as humans, and longbows are no harder to use than shortbows. If you think longbows are hard to draw, you're clearly thinking of composite longbows. I don't know anyone with a shortbow in real life but I know tonnes of women who use longbows and they aren't strong by a longshot.
It actually varies from bow to bow -- different bows do have a different draw weight. The real issue is that the D&D longbow is implied to be the same weapon as the English longbow, which required constant practice and above-average strength in order to use effectively.

D&D bows are kind of weird anyway -- the composite longbow seems to be more of a mash-up of bows produced by about six different cultures.

I don't particularly agree with the view that elves are just as strong as humans -- what the rules say an elf is seems to be at odds with what an elf would be on that front.