groups of words arranged together in a poem.
It is a group of words arranged contiguously and without concatenation from preceding or subsequent contiguous verbal arrangements.
They are called 'lines'.
No you can't take lines but you can take little pieces of the poem
No, there is not a period after every sentence in a poem. But I guess you could. A poem is supposed to be genuinly created by you. So do whatever you want to do.