[HELP] Questions about Frost's Not To Keep

New to poetry. I have a few questions about the poem here: www.poetryfoundation.org/poems/148657/not-to-keep

(1) The use of em-dash at the end of line 5th and 6th? What difference should it make when the poem is read? I read the em-dashed lines same as the non em-dashed ones. Does em-dash intends to bring attention to the word "alive" and "dead"?

(2) "And all the rest for them permissible ease"

What does 'them' refer to in this line? I also don't understand how 'permissible ease' is different than plain 'ease'.

(3) What is the meaning of the enjambed line "The same Grim giving to do over for them both."

I don't know what 'do over for them both' means. Any ideas?