well I have a few question I'd hope someone could have some answers here

I'm intending on moving to Finland in a few years to live there the rest of my life, I have my own reason but mostly I dont want to live where I'm at right now.
I have served 3 years in the army and about to work for the security department for about 3 years.
My best option to get a residence permit is work, as I intend to get a citizenship.
I intend to keep working as security department even on Finland as That is what I love doing (More of a special units kind of service)
My questions are;
1) Can I first come to Finland as a tourist and then find a job and get a residence permit through it?
2) Can I work at security job after I get a residence permit?
3) Would the police accept my apply with a residence permit? Or do I have to get citizenship? (Would it accept a forgiener to work for them?)
4) Can I buy an apartment or a house with just a residence permit or even without it?