I was wondering does the amount in a particular group effect it's probabilities of getting chosen over other groups, I know frequency controls the probs of a particular entry within a group, but I am talking about the overall groups. For instance group 1 has 10 entries, group 2 has 5 entries and group 3 has 1 entry, would this mean that group 3 has a far less amount of chance, like 1 out of 16, compared to the other groups or does it just use the group's as a whole, like 1 out of 3 chance since there's only 3 groups.

I only ask because it seems like some of the affixes like half-freeze length, which has one entry total in the entire text compared to other groups that have up to like 15 or more entries in one group, seems like it gets chosen far less. Am I missing anything or is this just bad luck on affixes.

The frequencies are not group specific, they are globally applied. You have to sum up the freqs for all possible pre/suf/auto-affixes (whichever applies) at a given ilvl. Circlets and other things with the magic level bonus overwrite the freq value this is why they not only have a level bonus, they also get inverse rarity on affixes making rarer stuff more common on them.

Thank you.