as you probably already know, we have an an special article concerning the coming new rule from January 1, 2019: https://www.a-kasser.dk/requirement-of-7-years-of-stay-in-Denmark-or-eea/
But to answer your questions, we can say that the new rule only applies for people who apply for Unemployment benefits ("dagpenge") after January 1, 2019. If you get unemployed before Januar 1, 2019, then it is the current rules that A-kasse must use, and in the current rules there are no similar rule/requirement like the new one.
Next, the coming new rules does NOT say that you must have been member of and paid to A-kasse for 7 years or for a minimum numbers of years. After January 1, 2019 there is still requirement of at least 1 year membership before you can apply for dagpenge.
Nor does the new rule say anything about that you must have worked in Denmark for some years. However for being eligible for dagpenge according to the excisting rules you must have worked at least for 1 year before you will be eligible for dagpenge.
What the new rule says, is that you must have stayed in Denmark for 7 out of the last 12 years, And in the first years with the new rule there will be a little slighter requirement, so you only need to have stayed 5 out of last 12 years in 2019, and 6 out of last 12 years in 2020, before the rule will be full phased in from 2021 with 7 out of last 12 years.
As a non-EU citizen you can only include periods with stays in Denmark or another nordic country (not stays in other EU-countries).