We can only see the information you choose to put on your profile, after you've been approved.
Some people have a phone number on there, but not many. The ones who do are usually those who prefer to communicate via text rather than Private Messages on P411 or email.
The majority of members I meet do use their real first name in their member ID but not all.
Unless you have a really unusual first name, there isn't much of a risk by using it, IMO.
On said profile, the only constant (required) information which is on every profile is:
Your Client ID
Your Preferred Name (what you want the ladies to call you)
Your Location
Email Address
Age
Ethnicity (pretty sure this is mandatory but not positive)
That's it. There are optional details you can provide, if you like.
There are also a bunch of questions; you choose which (if any) you wish to answer.
Please be aware that membership does not guarantee all ladies on that site will be willing to see you with nothing more than your membership. Some ask for additional screening information. If you don't like that, just move on to the next one because the vast majority of companions on that site do NOT ask for anything more.
I hope that helps!