Capital Gain Tax on Investment

Hello,

I have been living in DK for 3 years now. I have started investing into shares through international broker (Degiro.dk with my CPR registered).

There seems to be no concept of short vs long term capital gains here. Also dividend tax seems to be complicated.

I am married with my spouse not working.
I have few questions on share investment front...If someone could answer its great. If not, where can I get these specific answers from.

i) How should I do the tax returns with Skat on shares...given I might invest and sell it either within a day or few weeks or year. Sometimes, take profit from my share and reinvest later into the same stock if it dips. Does the shares data automatically go to skat ?

ii) Given I am married, are there any deductions/allowance when it comes to capital gains. Looks like 27% rate is for 100k gain or so.

iii) I invest in companies in US or Canada or Sweden. Does that impact the tax rate in anyway, say from dividends or stock sale.