Well, the Lazarus IDE itself is already modularized and plugable (even if it requires a recompilation), but the Lazarus distribution simply contains everything already.
To some extend maybe, but when new fpc rolls out, there must be used with a newer version of Lazarus), unless I am wrong (some time ago I did try to run newer fpc in 1.6 Lazarus but I got errors all the time).
About the settings; I use 2.0.2 as a separate install so I dont know if transfering older version setings is working/exists. But setting again the settings, plus the new ones tha come with every new version is frustating..
It's going to take some time to clean up my build, but one thing is sure: its messy. And dont take it the wrong way, I know that Lazarus is a project that takes a lot of personal time and resources, but a modular redesign would be much much better..