You can pass Toad env. variables into Execute Script actions starting with Toad 12.11. There are some examples here: https://community.toadworld.com/products/toad-for-oracle/b/weblog/archive/2016/10/18/running-scripts-with-parameters-in-toad-39-s-automation-designer
1) It can only be a select statement in the Export Dataset action. Yes, single query only. If you want to export multiple sql statements, then create multiple actions (or you can export multiple tables/views by specifying objects to export instead of a query)
2) not sure maybe someone else will answer this one.
3) it just means that the action doesn't have enough details configured for Toad to give you a meaningful hint about what it does.
4) not sure maybe someone else will answer this one.
5) There is no way to change the default semicolon statement separators in the export DDL/dataset action. However, Toad 12.12 will produce insert statements like below, so that blank lines inside of data do not cause a problem.
(EMPNO, ENAME, JOB, MGR, HIREDATE,
SAL, COMM, DEPTNO)
Values
(7499, ''||CHR(13)||CHR(10)||'/'||CHR(13)||CHR(10)||'', 'SALESMAN', 7698, TO_DATE('2/12/2018', 'MM/DD/YYYY'),
150, 300, 30);