Formatting two lyrics contexts without staff

[Svetlana Lobanova]

Dear lilypond users!

I want to align syllables of two text lines one under another without any note 
staff. Below is a working snippet, which is quite good for my purpose. I would 
like to gain some more control on layout: 
1) make some manual line breaks, 
2) add more horizontal spacing around syllables ,
3) make sylables to center vertically,
4) make ragged last line,
5) instead of 1 and 2 just set syllables count per line.
All these things usually are done in a staff. Is there a way to make such 
tweaks without any staff?

P.S. I know that lilypond is not a text tool, but I use the same line with my 
notes and would like to make this job automatically from the same source. The 
real use case is znammenny chant where I'd like to make original (neumatic, 
without notation) and dechiphered layouts.

\version "2.18.2"
\score{
  \new ChoirStaff <<
    \context Lyrics = "textI" {
      \lyricmode {
        b1 b1 bbbbbb1 b1 bbb1 b1 b1 b1 bbbbbb1 b1 bbb1 b1 b1 b1 b1
        bbbbbb1 b1 bbb1 b1 b1 b1 b1 bbbbbb1 b1 bbb1 b1 b1 b1 b1 bbbbbb1
        b1 bbb1 b1 b1 b1 b1 bbbbbb1 b1
      }
    }
    \context Lyrics = "textII" {
      \lyricmode {
        a1 aaa1 a1 aaaa1 a1 a1 aaa1 a1 aaaa1 a1a1 aaa1 a1 aaaa1 a1a1 aaa1
        a1 aaaa1 a1a1 aaa1 a1 aaaa1 a1a1 aaa1 a1 aaaa1 a1a1 aaa1 a1 aaaa1
        a1a1 aaa1 a1
      }
    }
  >>
}



-- 
Svetlana