1) In kind="con", the con stands for container, which is interpreted by eclipse as a classpath container. As described in that link:
A classpath container provides a way to indirectly reference a set of
classpath entries through a classpath entry of kind CPE_CONTAINER
In other words, it enables grouping of other classpath entries in any way and re-use it wherever (including the ability of having different entries for different projects).
2) exported:
Say you have Project B that depends on Project C. The dependency is defined as exported=true. Then, another Project A that depends on Project B, will have also Project C present on A‘a classpath.