Not in the way it was in the 70s, 80s and 90s. There are problems, but these are more in the political arena than in trouble on the streets.
Northern Ireland does not own any country. Northern Ireland itself is part of the United Kingdom, which may be what you mean.
At this time there are no national parks in Northern Ireland
No, Northern Ireland is a part of the UK.
Northern Ireland is part of the island of Ireland.
There is no toll charge on the M1 or any road in Northern Ireland.
The main division of conflict is between the Republicans (Nationalists), which are associated with Catholics, and the Loyalists (Unionists), which are associated with Protestants. However in recent years the Loyalists have become less active in conflict and any violence has developed into usually the Republicans targeting the security forces (Police/Army) in Northern Ireland.
No, as there is more Protestants than roman catholic in northern ireland. northern Ireland will always be apart of the united kingdom.
No! Don't be thick! And there isn't any need to write "the" before Northern Ireland.
If you mean is there border control between the Republic of Ireland and Northern Ireland then no there's not you can just drive across the border and not even know
The Professional Tattoo Academy in Northern Ireland could help you do a tattoo course.
It should be fine as it is. As long as your initial marriage is legal, there shouldn't be any need to register it in Northern Ireland. It will be recognised.
No. The Roman Empire got as far as Britain, Ireland's neighbouring island, but never reached Ireland. In any case, Northern Ireland only came into existence in 1922, long after the Roman Empire ended. It also ended long before Britain had any role in Ireland. So Northern Ireland was never part of the Roman empire.