Erm I would try removing blesta.php, remove database, remove user, remake them both, connect them both and try again, http://yourdomain.com/install/
If that fails I'm confused.
I've done a video for you.
Video Demo: http://screencast.com/t/wA7D6wbPVSaD
To get the API Code go to:
WHM (https://yourdomain.com:2087) and then go to Cluster/Remote Access then go to Setup Remote Access Key It's recommended to re-generate the API to make sure you have a fresh one.
Server name I put Titanic you need to put your full hostname in or IP depending on which you use eg: hostname.yourdomain.com or 1.0.0.2.7
You will still have that on your account for a while. http://account.blesta.com/ and log in with your phillipsdata.com/ams/ login you should have two licenses.
Owned Promo license (2.5) and a Owned Blesta license (3.0).
You need to set up a module like cPanel.
Link: /admin/settings/company/modules/available/
Click Manage then set-up a server, then a server group add the server...
Then on the packages, select cPanel > then server > then package.
You can't yet mate. The importer for WHMCS hasn't been completed yet for v3. The only way to do it would be using a v2.5 License (no longer issued I believe) to import from WHMCS and then import from v2.5 to v3
If Paul, Cody, Tyson allow me to lend you my 2.5 license and files to import to while you do it the longer way that's fine with me.
Yes however did you pay for a monthly license or a owned license? If it's a monthly license you will need to talk to them via support ticket, however you might have to wait so it's best to get a v3 trial license you can update when they get them as-well.
I've not tried customizing the backend with wordpress maybe something in wordpress is conflicting with Blesta. Shouldn't be hard though to do, if you can't do it, you could get a integration from Licensepal if they do it for Blesta.