Yes
You would need a visa to visit the United Kingdom in order to go to Belfast.
There are no border checkpoints now, so you can drive without being checked. Citizens of Northern Ireland or the Republic Ireland do not need a visa. However, if you have come from outside of Ireland or the United Kingdom, you may already have had to have got a visa to have got into either places first. That would depend on where you originally came from.
As Belfast is in the United Kingdom and Dublin is in the Republic of Ireland, technically you may need a visa or passport to go there, depending on your nationality or other factors. However, there are no passport checks done on the train. Usually if you have been allowed access to Northern Ireland, you will also be allowed to get into the Republic of Ireland, but you need to check. See the website at the link below.
No, Venezuelans cannot travel to the USA without a visa.
Yes, I've done it plenty of times
No, Jamaicans require a visa to travel to Canada.
Contact the Irish Department of Foreign Affairs. See the link below.
Yes, US citizens can travel to certain countries without a visa.
No, a green card holder cannot travel to Dubai without a visa.
no
No, Filipino citizens require a visa to travel to Canada.
Yes, Jamaicans can travel to the UK without a visa for short visits of up to 6 months.