I know some exceptional public defenders and some terrible private lawyers. But for that matter, I know some terrible public defenders and some exceptional private lawyers. Generalizations can't really be made about something like this.
Public defenders go to the same schools, pass the same exams, sit for the same bars as private lawyers do. The big difference is that you don't get to pick your public defender. You get the luck of the draw. On the other hand, if you pay for a lawyer, you can select the best one you can afford.
Public defenders handle some 80+ percent of all criminal matters, which is why they frequently get a bum rap. But they have to take every case that comes their way while a private lawyer can cherry pick just what he knows he can do well. So it's certainly not always true that a private lawyer can do better for a client than a public defender. It depends on the lawyers, the clients, and the facts and circumstances of the case.
In general, you're not going to find a very good private lawyer for 4 felonies with only $2,000 to spend on the lawyer. If this goes to trial, spending 5 times that or more is likely.
In some situations, the quality of the lawyer makes a big difference. With a difficult case that has to be tried, you want the very best you can manage, and that would usually mean a private lawyer, as they are less busy and can devote more time to the case. If trial is unlikely and the lawyer is just going to be negotiating the most favorable plea bargain possible, spending a great deal of money on the lawyer is less important -- assuming, that is, that the client and his public defender are on the same page as to what they want to get from the state.
So, if this case is likely to be pled out, and your son has a public defender who is working very hard for him such as the last one you mentioned, and he's happy with the level of representation that he has got, that's valuable and I wouldn't be so quick to replace him or her.
2) statements made over the phone are hearsay and not admissible at trial, however, if your son were to make a confession, then that would be an exception to the hearsay rule and could be usable.