2.10 questions

[Monk Panteleimon]

Many thanks to the  all the diligent developers and users for 2.10 and the 
previous versions.

I'm now running 2.10 on xubuntu (ubuntu 6.06) and I have several questions 
about lilypond 2.10:

1. It looks like hairpinToBarline is set "true" by default. The "changes" doc 
makes it sound like you have to turn it on to get it to work:
"By setting hairpinToBarline, hairpins will stop at the barline preceding the 
ending note."
I assume that it was intended to be set ##t by default, and the docs are just 
phrased from a 2.8 point of view. If this is so (here's the question) is it 
##t by default because that's the common consensus of traditional old-school 
engraving -- or is it just 'cause? 

2. It looks like you can't put \tempo= inside \
midi{ } anymore. Lilypond complains about it in my 2.8 files, and after I've 
run convert-ly, I see it replace by something like this:

  \midi {
    \context {
      \Score
      tempoWholesPerMinute = #(ly:make-moment 90 4)
      }
    }

The 2.10 manual (p 232) seems to say that only the \tempo command that goes 
with the notes (producing a metronome mark unless forbidden to do so) affects 
the tempo of the midi file. The manual's a little confusing here actually, 
because the example shows the curly brackets empty for the midi block, and 
tells us that in this example the tempo is set to 4=72. How? By leaving it 
empty? So 72 is default?  What am I missing? 

So, the only ways to set a tempo for the midi file without adding a metronome 
mark are to add and a metronome mark, but make it invisible, or else do that 
kind of longish thing with the scheme-indentifier in it, wherewith convert-ly 
replaces the old \midi{ \tempo = ... } deal. Right? 
Is there a shorter way, or can I somehow re-instate the 2.8 method in my 
lilypond installation? I often make midi files, but rarely require a 
metronome mark. 

3. When I run 2.10 on any files (before or after convert-ly) I get lots of 
messages that say "programming error: no solution found for Bezier 
intersection, continuing, crossfingers"
The files still compile, but I wonder if it's okay to uncross my fingers now.
[8^)>

4. (the dumbest question of all) Why 2.10? What's wrong with 3?

Thanks again. Please pardon my verbosity and probably my utter density 
regarding all of the above. 

Fr. P

PS. My, what lovely shapenote heads!