If I have a table.el table, is there any way to set the LaTeX table
environment for it (longtable, tabularx etc.)?

Here's a simple sample:

* Table Test

This is a table.el table:

+---------+-----------+-------------------+
| Test    | Test2     | Test3             |
+---------+-----------+-------------------+
| this is | some text | in the table      |
+---------+-----------+-------------------+
| here is | some more | to make it longer |
+---------+-----------+-------------------+


-- 
Gary