Church Slavonic Prepositions

This is a table of primary prepositions and their central meanings. It is adapted from a similar table in A Comprehensive Russian Grammar by Terence Wade. Since this was based on a Russian grammar, I do not know how well the Church Slavonic prepositions correspond to their Russian equivalents or what spelling differences there are between the Russian and Church Slavonic forms. Please let me know of any inaccuracies.

Preposition	Genitive	Dative	Accusative	Instrumental	Locative
	without
			into, for		in, among
	for
	as far as
			because of, on account of	behind
	out of
-	from behind
-	from under
		towards
	except for
				between
			on to		on
				above
			against		around, about, near
	from
				in front of
		along	up to		after, for, for the benefit of
			under (motion)	under
	in the midst of
					in the presence of
			about
	for the sake of
	down from		down from	with
	at
			across

Questions

What are the rules for using the <o> suffix on single-letter prepositions (e.g. v" and vo, s" and so, k" and ko, etc.)?

Why is <vo vjeki vjekwv"> used in one place (e.g. <Slava i Nynje>); and <v" vjeki vjekwv"> used in another (e.g. Psalm 83:5)? Psalm 47:15 has both in the same verse, <vo vjek" i v" vjek" vjeka>. What is going on?