don't worry, that's what these forums are for.. to seek advice/help from others.
there are a handful of postbac programs.
1. where? various locations (ucsf, baylor, temple to name a few) some programs are formal others are informal, meaning there are commitments or not.
2. usually they are just undergrad classes to help bring up ur gpa or retaking classes u did poorly on. u can earn a 2nd baccalaureate degree if u take enough classes (similar to double majoring)
3.GPA should be calculated just like your undergraduated courses.
4.every school has a different timeline in terms of appliaction. you google "post bac" to find out which schools are available around your area and its timeline. no, i don't think u would need to take the gre.
things to note:
*some schools do require that you have had applied to dental school unsuccessfully
*some require that you are from a disadvantaged background
*some require a 1 yr commitment in their program