How to parse 彼は甲殻のように固い背中を下にして横たわり

Question

I am (still) reading Metamorphosis(from Kafka) and can't figure out how to parse

彼は甲殻のように固い背中を下にして横たわり

Translated as

He lay on his armour-hard back

I suppose the japanese version litteraly looks more like

He lay on his back hard as a nutshell (or is it "on his hard back which looks like a nutshell" ?)

Here is what i don't understand :

1. How to parse のように ? i know about ように ~ "trying to do something", Aのよう　~ seems/looks like A (exemplification) and the adverbial ように but none of them seems to apply here : am i wrong ?
2. Does に in 背中を下にして横たわり make 下 into an adverb ? If not what's its meaning ? And if so then see 3.
3. What's the use of を particle here ? Doesn't 下にして横たわり already have the sense of "to lay on his back" without the 背中を part ?

Answer 1

1. The main confusion is that Xのように in this context means "like/as X" rather than anything related to "trying to do".

2. Xを下にして here means "with X facing down". を indicates that the thing which is facing down is 背中, his back.

Breaking this down, we have:

甲殻のように固い
As hard as a carapace

甲殻のように固い背中
(his) back, as hard as a carapace

甲殻のように固い背中を下にして
with (his) back, as hard as a carapace, facing down

彼は甲殻のように固い背中を下にして横たわり
lying down with his back, as hard as a carapace, facing down