First, the answers to your questions:
1) I understand that if I am hired, I could be the 2nd, the 9th, the 25th, or 104th person hired - you need multiple developers for this project, and every developer hired will be paid. In other words, not being selected first does not mean not being selected at all (I can be selected later).
2) My approach is to look over the project, fix any obvious errors, ask questions about any code that is unclear in the sense that it could be coded multiple ways depending on what the client needs, use Perl::Critic to uncover any standardization issues that could stop the program from running, then run the program, see what errors still exist, find the root cause of each error and fix that error, and repeat until we have a runnable program.
3) I have recent experience with Perl 5, PHP 5, Java 9, Scala, and JavaScript. I have also worked with VB.NET, C#, VB6, Kotlin, Perl 6, C++, C, Assembly (Intel and PDP-11), APL, and LISP.