Voice alterations and temporal dieccis problems

Merhaba!

1. Since voice alterations only alter emphasis of arguments of a sentence, John
Quijada suggested I only use the emphasis particles (in a certain conlang).
Then I thought of 'doctor vs. patient' - converses - and then realized things
like 'I own a book' and 'A book belongs to me' are the same thing, except that
the latter is 'I own a book' just with emphasis on 'book', whereas the first
sentence emphasises 'I'. If emphasis alteration will work for verbs, will it
work for nouns?

2. In the same language, I'm stuck on how to derive 'now', 'then (past)', and
'then (subsequent)'. Will deriving them from 'here', 'there', and 'there (over
there)' work? Or will it be idiomatic, or not make sense? I think of 'now' as
'at this time' and 'here' as 'at this place', so what about the others? I'm
thinking 'then (past)' = 'at that time', 'there' = 'at that place', 'then
(subsequent) = 'at yonder time', 'there (over there)' = 'at yonder place'. The
third one just doesn't seem right to me.

--Trebor