If I’m meeting with a laywer today for legal advise on getting full custody of my son but only have 15 minutes with him, what questions should I ask?

The first thing you should ask for is more time.  For an attorney to get a better idea of the facts of your case and for you to get a good feel for the attorney, you need to spend a bit longer with the attorney. 

Questions for you to ask the attorney generally would include:

1.  How long have they been practicing family law.

2.  Do the regularly practice family law in your jurisdiction.

3.  What is their billable rate and when is payment expected.

4.  For cases similar to yours, about how much does the total amount generally run.  (They may not be able to give you an exact because every case is different, but they can give you an estimate)

You also need to spend time talking to the attorney generally about your case.  Areas or questions you want to cover include:

1.  The reason you are seeking custody.

2.  Whether or not there are any orders currently in place.

3.  If you did not get custody the first time around, what was the judge's reasoning... and if there were issues, have they been resolved.

4.  Are you prepared to take full custody-- financially do you have the resources, do you have enough rooms in your house, do you have a way to get them to school in the morning, etc.

5.  What are the issues with the other parent and how long have those issues existed.

This is a sampling of questions to get you started on some good conversation with the attorney.  Every state decides custody on what is in the best interest of the child.  As you are talking to the attorney, find one that you are comfortable talking with and that seems to listen to your concerns.  If this attorney is already regulating your time to 15 minute sound bites, they may be more interested in the billable hours than what's really important to more your case forward.  If this one doesn't work out, keep looking for one that fits your comfort level and needs.