Starting a sentence with "One question..." and then stating the question?

I am wondering about proper grammar in this case. Or if I should just avoid starting a sentence with “One question…” (my gut tells me I should).

Here are some examples:

One question you could research is, do female birds mature more quickly than their male counterparts?

I believe it is proper to end with a question mark there, and I put the comma because I also believe that is correct grammatically. Although I feel perhaps a colon would be more suitable?

and another example:

One question you could research, and whose answer I am particularly interested in myself, is: Do female birds mature more quickly than their male counterparts?

In this second example I am particularly interested in whether I should have a colon after “is”, or if a comma (or nothing) would be better?

So to restate my questions: I am wondering whether the examples are correct, or if there are any suggestions/corrections regarding them. Additionally, is starting a sentence with “One question…” is okay, or should I avoid doing so for some reason?

Thanks.

Bonus Example: (I am okay if what follows is ignored/not answered, but I don’t think it warrants an additional question so I’m asking it here).

Consider the following:

One question you could research is: what impact does doing ten jumping jacks a day have on a person’s lifespan?

vs

One question you could research is what impact doing ten jumping jacks a day has on a person’s lifespan.

I don’t know if the second formulation is correct or not. If it isn’t, why is it incorrect? If it is correct, why do I not need a comma or a question mark at the end? Did I reformulate the question as an indirect question? (I’m not clear on the distinction between direct and indirect question yet, sorry).