Mixed questions

[Matthijs Frankena]

Hello,

After a long pause (stopped at 2.4) I have taken up Lilypond again. 
Great improvements in the meantime, and I certainly like what I see as results.
However, several things still have me stumped, even after searching 
through the manual and the userlist.
I refer to the attached .zip, containing the .ly-file and the 
resulting log and PDF (parts of a song that I try to copy to get some 
practice in setting seemingly easy music).
Configuration: Windows XP/SP2, Lilypond 2.8.1

- I want the text in header:composer and header:poet to be 
center-aligned. However, the text then seems to be centered along 
what ordinarily would be the left margin, and winds up too far to the 
left. Is there a way to move these texts to the right?
- I would like one bar to end with "||", and the following one to 
begin with "|:" (bar 12/13) like in the original. But... one seems to 
cancel out the other (explicitly setting "||" cancels the "|:" from 
the repeat). Any tweaks to accomplish what I desire?
- In the second alternative of the repeat, the first bar in the right 
hand (bar 17) should start with the end of a slur (that started in 
bar 14). There does not seem to be a way to end this slur (and 
Lilypond complains about it in the logfile), like there is for ties 
(\repeatSlur like \repeatTie). Or did I miss something?

I would greatly appreciate pointers to solutions, sections of the 
manual that I have missed, or threads in the discussions that offer 
the solutions I look for.

TIA,
Matthijs Frankena

Test.zip
Description: Binary data