<p>I don't know about other schools seeing where you apply, but you should apply online if you can. Colleges actually prefer it as the information gets processed faster and they don't need to deal with handwritten. Most colleges probably won't consider where else you apply to either.</p>
<p>It doesn't really matter. I chose to mail mine because my school required a print out with a signature, check and photo mailed in. So I figured if I was mailing something, why not mail the whole thing. </p>
<p>I really don't think it matters. It's more of a personal preference. I didn't feel comfortable submitting online, so I chose to mail. It worked out fine for me.</p>
<p>Online I would do it early enough to make sure that the site works at all (UChicago's didn't seem to ever work last year) and isn't overloaded. If you see they acknowledge your application, then all is well. (One place last year claimed that a preapplication my daughter did online was never made, but it was easy enough to redo it. She had the time.)</p>
<p>If you mail, consider making a copy and FedExing the original. It doesn't happen often, but sometimes the things get lost in the mail (or by the school). I've heard from other parents about this happening to their kids. For my daughter, one school didn't acknowledge receipt of her application and claimed it hadn't been made. When I called with the FedEx confirmation in hand, they were willing to search some more and ultimately found it.</p>