Is a question that essentially says "Explain X" a good question to ask? I'd be doing it in the interests of populating the site, rather than because I actually need to know myself.
While the questions may prove useful, I would be wary of the timing of asking such questions early on.
This site is still in Beta and needs to attract an audience to succeed. The questions on your site say a lot about the community. To attract experts, you need a site where people are asking very interesting and challenging questions, not the basic questions found on every other Q&A site. Your goal is to make it clear that this is a PRO site.
Ask real, expert questions.
When potential members visit the site for the first time, the front page is going to tell them if this site asks interesting questions... or not. You want them to say, "Whoa! This is a site for me!" Questions like "What is a 401(k)?" or "How do you buy stocks?" are not going to accomplish that. Ask those questions when the site becomes a canonical source for all things financial.
You can read more about this stuff here: Asking the First Questions.
I personally am wary of blatant seeding. I do seed some, but mainly with questions I've actually had (even if I've already answered them). This keeps the site honest and organic.
As long as the answer is text written here, then it should benefit the site and further goals of the site.
If the answer ends up being a more links away (more than just references) than full paragraphs I don't know if that is as helpful.
For example, money bloggers should come here and write detailed answers with examples, and then link to their personal blogs for some traffic if they wish. However answering with a sentence that links away to another blog isn't what I would hope for.
I would try to find a more specific question you have on that topic. In order to get to that question would explain some of the basics about X like "I know this and that and such and such about IRAs, but does that still apply if yada yada yada?"
I did something like that in this post. Not that it was a seed question, but I just felt like I needed to give some background of where I was coming from before I could ask the real question. Which in that case was basically 'Am I on the right track? And how can I improve my approach on this?'
I also like to make a habit of including some basics about the topic embedded in my answer for the sake of readers who might be new to that topic. It also keeps people from telling me those basics and thinking that it would help answer my question.
I like them as long as it doesn't become overwhelm other useful questions.
They hurt anything and I they ought to help promote the site through search engine traffic.