It depends on how the first link is treated; links from profiles are often set as 'nofollow' and so pass no value to the target page.

Quickly checking on Quora, for example, they use a 'nofollow' tag on their links from answer contributor names.

If you change your domain then expect your rankings and traffic to drop significantly for at least a short period of time (a few months is likely). You'll need to set up 301 redirects from the old domain to the new, pointing to relevant replacement URLs on the new domain; .us/how-to-redirect => .com/how-to-redirect

The .us domain will help focus on a US market, though a .com will also do the same. The differences is a .com is also international, so users from the UK, France, etc may still feel comfortable dealing with a .com domain, but may not with a .us one.

The most important thing in terms of SEO is the users' experience in finding the answer to their query; too many people focus on using '-' in their URL in order to get the perfect, keyword rich domain, but Google actually looks for the speed and efficiency in which you can answer a query for "easier routes from IL to KY".

.com, .net, .org. They're all pretty much the same in terms of value; they're all TLDs. The key difference in them is how your users react to them; a charity/public service website may see better results by using a .org for example, but a multinational corporation would likely only settle for .com or .net.

Rena,

As mentioned above, this is due to the only difference in pages being the HTML for the feature image. A way of fixing this (and potentially improving conversion/enquiries too) would be to detail the item; what kind of paper stock does it come on, what colours can be provided, are there set types of font, and so on?

Do you have clients who are willing to provide a few words on their opinion of the item which could be used as unique content on an invite's page?