Hi,
1. there is no minimum payment. So you will get 90% of your previous income. In the calculation the A-kasse will use the "best 12 months within the last 24 months".
2. No, not if it is 4-5 years since you received dagpenge last time.
3. If you move to Denmark and are entitled to dagpenge in Denmark, then you will get the amount that is calculated according to the calculation mentioned above. What your are entitled to in Finland is not relevant.
4. If you have been member of an danish A-kasse within the last 5 years, then you can transfer your rights (membership period, and working hours/income) from the finnish unemployment insurance system on the day you arrive in Denmark. You do not need to work in Denmark 296 hours before you can transfer your rights.
5. Within EU, you are only allowed to be member in one A-kasse (unemployment Insurance) at a time, and that must be in the country where you work. So as long as you are working for a finnish company/have your work-place in Finland, then you shuld keep you memberhsip in Finland. But if you can transfer rights then it should not give any difference if your are member in Denmark or Finland.
When you have a relative low income, then you must be aware that for being eligible for dagpenge in Denmark you need to meet the "income-requirement". This means that you must have earned at least DKK 233,376 (in 2019) during the last 3 years (in total). Only periods with membership (in Finland or Denmark) can be counted to fulfill the income-requirement.
Best regards,
Anders Weber, www.a-kasser.dk