The answer to the upper level: it is completely a matter of taste :-)
Personally for "internal" projects (you have some control over other developers' environments), I include Eclipse files with the caution that you must be sure that everyone uses relative paths in their configurations. (Every few months we had a build break because the library path was hard-coded, it took a few seconds, but it was unpleasant.) I also usually used a lot of things like Eclipse code formatting and compiler warnings to simplify life (for example, huge Subversion checks, because one of the editors fell into the battle for formatting tabs).
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svn://someplace.nn/projects/MyProject/trunk —> source
svn://someplace.nn/projects/MyProject.control/trunk —> project control files
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