I'm not sure I understand your two other questions, but here's an attempt to answer what I think you're asking.
Each of the major haplogroups has subgroups. For example, I1a4a, I1b1, and I1b1a2a are subgroups of I1. All of these groups are thousands of years old. All of them are spread throughout Europe, but more concentrated in some areas.
You can never figure out exactly where in Europe someone was from just by knowing that they were I1a4a, I1b1, or I1b1a2a. The best you can do is look where the male-line ancestors of modern men lived to see where those groups were concentrated.
For genealogical purposes, haplogroups are (almost) irrelevant, except to see if two men might have been related through their fathers' lines. Members of the same haplogroup have to be related (by definition), but usually it's so distantly that it's beyond the genealogical time-period.
There are two times when it makes sense to look at the haplogroup.
First, if two men belong to different haplogroups then they are not paternally related.
Second, If two men belong to the same haplogroup then they are related but you don't know how closely. Could be tens of thousands of years ago. To figure out how closely related they might be, you compare all the values of all the markers for men in the same haplogroup.
The haplogroup helps you weed out the people who look like they match but who really don't.
So, if you are I1, the first thing you do is whatever testing you need to see if you might belong to a more specific group. Maybe there is no subgroup, and you end up plain I1*. Or maybe you find a subgroup and it turns out that you belong to I1a4a, or I1b1, or I1b1a2a, or whatever.
Once you know your most exact subgroup, you can compare your marker results with other members of the group. It's controversial, but you can get a general idea of how far back the relationship might be. For example, if you match 64 out of 67 then you are probably related some time in the last few hundred years. If you match 67 out of 67 you are probably fairly close relatives.
These numbers are just examples. There is a dispute about average mutation rates at specific locations, and about whether this kind of analysis is even valid on an individual level. But, the basic idea is good. The closer the match, the closer the relationship. The more distant the match, the further back the relationship. In fact, most matches aren't very close, so the relationship goes back before recorded history.