Slur adjusting

[Anna Choma]

Hello,

I write a piece of Wagner, where there is many many slurs. To make
them look better (without collision with staff lines, accidentals,
other slurs and ties, to make them stick to notes) I use such
predefinitions:

\override Slur #'extra-offset...
\override Slur #'height-limit...
\override Slur #'control-points...

My version of Lilypond is 2.4.5 and my questions are:

1) How to revert the influance of such definitions after using it and
after the changed slur? I have problem especcialy with control-points
-- all the next slurs are changed. I have tried to use \once before
the override command, but then changing next slurs with another
command doesn't work at all. I've tried also putting the slured notes
into brackets { }, it has no effect either.

2) Is there any good method of changing slur curvature and slur
beginning point and ending point? Only control-points?

3) Why the slurs so often doesn't stick to notes they belog to? Am I
doing something wrong?

Best regards,

Anna Choma