Inside EU you vote in your country of residence or in the country you have citizenship. You can choose.

If you move out of EU you vote in your home country. I guess the exact procedure depends on your home country, some allow mail ballots others require you to come to the embassy.

If you live outside the EU, you can usually vote in the EU elections in your home country's embassy or consulate. However, some countries don't allow you to vote from outside your home country.

Depends on country but for Finland for example they can. Alternatively they can vote in EU country they are resident in, if they sign up for that.

Don't know if you are asking this because of general interest or if it's specific for this MP, so just FYI: While your opinion might align with him on this topic he has some very outspoken opinions on other topics where you might have a different opinion (or not).

For example Rob Roos is also an very outspoken anti-vaccine and against climate legislation.

No