Most of my changes are not necessary, just useful.
1. Last year I built SheepShaver in Tiger. It works in both Tiger and Leopard. I did not use an SDK. Why should that now be different if I again would build in Tiger? Maybe this is only needed when building in Leopard? Or could the fact that I have XCode Tools 2.5 installed in Tiger be relevant?
This just lets you build on Leopard, yes. But the same technique works for building on Tiger/Leopard so it works on Panther, or building on Snow Leopard so it works on previous versions.
2. I built the Intel version on my iMac and the PPC version on my PowerBook. Combining them using lipo was easy.
That's fine, but using -arch would let you build both on the same machine.
3. What about the other differences with how I compiled SheepShaver last year? Are they related to recent changes in CVS or is there a different reason?
--disable-standalone-gui (not needed last summer)
--enable-vosf (needed to be "--disable-vosf" before)
--enable-addressing=real --without-esd --without-gtk --without-mon --without-x (not yet last summer)
--disable-standalone-gui is because there is now an integrated GUI. But maybe people using fullscreen mode would appreciate having a standalone GUI.
On my machine, --disable-vosf is faster than --enable-vosf. But either should work, up to you.
The other options look ok.
4. No SDL framework in SheepShaver.app/Contents/Frameworks in previous builds, why is it needed now?
It's not needed, but Apple recommends linking against internal libraries rather than building statically.