Adding these query elements will greatly enhance the capabilities and performance of the complex queries being developed to support the various Events.
Cross Apply is essentially a Join used to link a table with a Table Valued Function or subquery with the ability to reference the outer query for each row.
Cross Join (and Join ON 1=1) would allow for a cartesian join of two tables such that all combinations are selected. This could be achieved with the existing Joins by just adding the ability to specify the 1 = 1 condition for the Column Name and Linked To Column.
Union (All) supports the merging of two datasets with the same column definitions.
I need more detail on the use case on this please.