Hi, new here, 58 and hate it.

I wanted to ask a few questions concerning niacin. I have already researched the heck out if this, but you don't know what to believe or not, plus asking this i can get answers that are tailored to what i want to know.
1-Is there any worry about niacin side effects or stopping/starting niacin if you are taking amounts around 50mg or less?
2-I read not to break tablets in half or open capsules and take it like that. Why do they say this? I have 500mg capsules and would like to open the caps and sprinkle tiny amounts such as 120-50 MG on my food once a day. Any reason i can't do that, and why do they say not to?
3-i want to take it to help with my blood pressure. But most of what i read doesn't mention that. Some does, but most concentrate on cholesterol control. Does niacin in small amounts like i mentioned help with BP at all?
Thank you