Well, i have never run into the issue with XAMPP that you describe, I just checked the tutorial for installing XAMPP and it does direct you to the Apache friends Site, but i have never had the installer try to force me to enter a mobile phone number.
did you try creating the php page as i described with the phpinfo() code on it?
this is they way to find the active php.ini file and make sure that you are editing the correct one.
the cURL test is run on the server that you access for the install. are you accessing localhost to run the install or another website address? how about this: What is the address in the address bar when you see the error that cURL is disabled?
The test will try to load a cURL connection to the webassist servers, if it cannot connect to the webassist servers, it will return the cURL error message
