I would suggest using the top heading to make it clear what this page is and what the user is doing on this step; confirming the information they provided.
I think there is a good argument for both placements of the alert message:
At the top:
The user is immediately made aware that they have to carefully read through the information they provided because by clicking on "continue" they are confirming that the information is, in fact, correct.
If we compare this to a shopping mall where you are reminded at the entrance by a sign that says "Please leave shopping bags/carts here when exiting the store", then visitors are made aware when entering the store that they have to leave their bags/carts here when they are done shopping.
The disadvantage of this, is that I can imagine that if someone is in the store for 30+ minutes it is easy to have forgotten this message and not remember where to leave their bag/cart.
At the bottom:
If the alert is at the bottom, right above the "Continue" button, then it would serve as an extra reminder to make sure the information is correct.
The visitor is then not alerted at the entrance of the store, but at the exit when leaving the store. This is really helpful, because this is exactly the time when they need this reminder.
The disadvantage for this option is that a digital form is not perfectly analogous to a physical store, and for long forms it would add extra frustration to find this reminder all the way at the bottom of a long page. Undoubtedly, some users will feel they have to scroll all the way backup to scroll through the information again to really make sure they didn't miss anything.
I don't think one option is necessarily better than the other, and it mostly depends on the length of the form. I also think that copy can make a huge difference. If you use good copy at the top, and add a clear reminder at the right time (right before continuing) that would go a long way.
I would also strongly suggest to avoid using italics, because this would reduce legibility for a number of people. Use font-weight and color/contrast to illustrate importance instead.
Here is a quick demo I made to visualize the idea in my head: