Those are fair questions and I grant that I haven't the faintest idea other than to fall back on some unsatisfying "angels" or "heavenly forces."
Imagine if you (generic) had to watch a movie of your life and recognize each of the moments and actions that were contrary to divine will and fess up to that. You would be ashamed but would have to "grow" in the sense of understanding your actual relationship to the full divine presence.
In terms of the groupings, we assume that there are very few who are truly evil (speaking about from among the Jewish people -- I'm not deciding if Hitler's soul is educatable or not). The 11th chapter of the talmudic tractate Sanhedrin goes through categories and individuals who have forfeited some aspect of the next world. I will quote a summary of the Mishna (the heart of the oral law) but there is substantial explanation and explication regarding this so please don't jump to any conclusions about meaning from just reading the isolated version I am pasting:
The following have no share in the world to come:
1.One who says that the Torah does not teach that there is a world to come, or that Hash-m did not give the Torah, or an Apikorus;
2.R. Akiva says, even one who reads foreign books (this will be explained).
3.One who whispers "Kol ha'Machalah... Lo Asim Alecha Ki Ani Hash-m Rofe'echa" over a wound.
4.Aba Sha'ul says, even one who pronounces Hash-m's name like it is written.
(c)Three kings and four commoners have no share in the world to come:
1.The kings are Yarav'am, Achav and Menasheh.
2.R. Yehudah says, Menasheh has a share in the world to come, for it says "va'Yispalel Elav... va'Yishma Techinaso va'Yashivehu Yerushalayim l'Malchuso"!
3.Chachamim: He returned him to his kingship, but He did not return him to life in the world to come.
4.The commoners are Bil'am, Do'eg, Achitofel and Gechazi.
The bottom line is that it is subject to books and books' worth of discussion and argument. As to what non-Jews don't ever qualify (and yes, not all the people listed above are Jews) that is also the subject of discussion -- are those 4 listed archetypes or is it a closed list.
As to the other question you asked about
Why would someone want to be Jewish if they weren't focused on the afterlife? I thought the whole point of being in a religion was so that you got a chance at some afterlife.
that is easier to answer -- Judaism sees all people as having the opportunity for an afterlife, not just Jews. As such, there should be no draw to convert to Judaism based on getting a chance at anything in particular.