What is this plant? How should I trim it down?
#1
What is this plant? How should I trim it down?
These plants have been steadily growing since I moved in a few months ago. Are they weeds? They have grown a few feet and I'm afraid they will take over the house. Should I keep them? If so how should I trim them down?

#3
I am undecided on whether I like it or not. But I definitely want to trim it down without killing it in the meantime. Does it matter how I do that?