life forever.

Means: That is that type of life I want forever.

 Let the blow fall soon or late,/Let what will be o’er me

Means:  It doesn’t’ matter when I die, earlier or later.  Whatever will be, will be.

 Give the face of earth around/And the road before me.

Means: Give me the earth, the great outdoors, around me everywhere, and the road before me to travel.

 Wealth I seek not, hope nor love/Nor a friend to know me.

Means:  I don’t need money, love, or even friends.

 All I seek is the heavens above/And the road below me.

Means; All I want is the great outdoors and the road to travel.

 Or let autumn fall on me/Where afield I linger

Means:  Let the leaves of autumn fall on me wherever I may have stopped at that time

 Silencing the bird on tree/Biting the blue finger

Means: As autumn changes to winter, the birds disappear, preparing for winter

 White as meal the frosty field/Warm the fireside haven

Meaning:  And when the fields are covered with snow, I will have a fireside shelter outdoors.

 Not to autumn will I yield/Not to winter even!

Meaning:  I will not allow autumn and winter to force me indoors.

The last stanza is the same as the second stanza.

In "The Vagabond" by Robert Louis Stevenson there are a number of tropes, which are figures of speech that include metaphors and similes, but there are few metaphor or simile tropes. There are however unusual vocabulary words from a Scots dialect, like lave and blow, that might possibly be mistaken for metaphors if the definitions are unknown: Lave is defined as a flowing water as in a river, and blow is defined as a storm or a strong blast.

There are several instances of personification ("Give the face of earth") and a few metonymies (e.g., "blue finger" for frostbite), but there is only one simile and only one metaphor. A simile makes a comparison between two unlike things and uses the words as, like, such as or though to draw the comparison: e.g., love though thorns is sweet; candies such as god's ambrosia; clouds like trumpets; soft as goose's down. A metaphor likewise makes a comparison between two unlike things but omits any connecting word thus indicating only that one thing is another: e.g., light is bliss; dance is life; love is roses.

The one simile in "The Vagabond" is in "White as meal the frosty field." Here, white meal, or white flour, is compared to a field that is covered in frost: To the poetic speaker and the poet, the field covered in frost looks like it is sprinkled with white flour over it.
The one metaphor is in the next verse (i.e., line), "Warm the fireside haven." Here, the fireside is compared to a haven, which is a resting place, a sanctuary or a safe harbor.

Bear in mind the context of these tropes indicates that even though autumn may bring the bite of "blue fingers" with fields covered in frost, and even though the fireside is a warm sanctuary, the speaker will not yield to autumn nor even to winter ("Not to autumn will I yield, / Not to winter even!"); he will instead live with "the heaven above / And the road below me."

Robert L. Stevenson's poem "The Vagabond" describes a life for which he yearns. Often, the vagabond lives his life wandering and longing for something that he may not even understand.  However, this is not the case in this poem.  Stevenson describes exactly what he wants from the rest of his life.  The tone of the poem enthusiastically describes a life filled with a desire to bond with nature and no burdens from society. Each verse leads to that understanding:

• Stanza 1:  The narrator wants to live forever under the skies, making his bed along side the road looking up at the stars.  He is a man longing for solitude.  Obviously, he loves nature and desires to always be a part of it.
• Stanza 2 and 4: This verse is repeated twice.  Apparently, the message is at the heart of the poem.  He knows that death (the blow) will come for him sometime:  "Let what will be o'er me..."  As long as the poet finds himself surrounded by land and nature,  he will surrender to  whatever comes to him.   Money, material things, friends, love...none of these things interest him.  All he needs is the open road before him. 
• Stanza 3:  When the season changes and nature has to yield to the elements, the poet still will not give in. He mentions the bitter cold and a fireside to warm him...but still he will not surrender his vagabond life. 

The poem has a lyrical quality much like the old shanty tunes of the past.  In fact, the poem has been put to a melody by Schubert.  Wanderlust finds all of us  at sometime, wishing that we were here or there.  However, this narrator has more than just a dream; he craves to be a part of nature and the untethered life of the vagabond.