I have never actually done a page with multiple EBD or CF7 forms on it. However, I have seen other people do it, so at least it used to work in some configuration somehow ??
Ok, looking more closely at the html in your page, I do see that each download has a different value for download_id (which actually gets turned into _wpcf7_download_id in the html). So, on the first one, it’s a _wpcf7_download_id of 2, the next one is a 3, and so on.
Regardless of which download button I click on and then fill in the form and submit, it always sends a _wpcf7_download_id of 2 (which, as you said, is the first download). Using Firebug, I changed the value of the first download from 2 to 4 in the HTML and then I clicked on the bottom/last download button, filled in the form, and hit submit. This time, it sent a 4 for _wpcf7_download_id and I got a different PDF file.
So, it looks like regardless of which Submit button you hit, it is actually always submitting the first form on the page. That sounds like a javascript event handler interfering to me. Not sure if that’s coming from Contact Form 7 somehow or if it’s related to your popup forms or your antispam plugin or something else.
I think at this point, your best bet is to make a new test page with 3 or 4 of your forms on there (like your existing page) but don’t do the popup thing and see if that fixes it. Also, check the CF7 support forum and see if there’s anything about multiple CF7 forms on the same page.
ps – on your slow email issue, your hosting provider may say that the problem is with the recipient doing virus scanning on the incoming email. However, I made it send to one of my servers that does no processing on incoming email and I watched the mail log file and could see that your system didn’t even attempt to connect for several minutes, so the problem is definitely on your end.