CallableStatement, OUT parameters and passing non-JDBC parameter expressions as arguments - how does indexing work?

Question

The documentation seems very vague on the interaction of stored procedure's OUT parameters with various other JDBC features. Do I presume correctly, that index passed to a registerOutParameter method has to be the 1-based index of the procedure's parameter, and is not the same as the index of PreparedStatement's parameter passed as the argument for that parameter? There is a potential for discrepancy/ambiguity when the argument for a procedure is a literal (or an SQL expression non-dependent on JDBC parameters), or when the argument expression depends on two JDBC parameters.

c.prepareCall("{? = call myfunc(?, 1, ?, ? + ?, 2)}")

1. In the example, if the last three parameters of the procedure are IN/OUT parameters, the indices that should be registered are 1, 4, 5, 6 - correct?
2. If I switch to procedure syntax of {call myfunc(?, 1, ?, ? + ?, 2)}, they go down by one to 3, 4, 5 - correct?
3. By experimenting I found that cursor OUT parameters can be retrived by (ResultSet) getObject(i), except when it is the return type of the function, in which case it becomes simply 'statement.getResultSet`. Is this behavior vendor independent?
4. If a CallableStatement is batched, can OUT parameters be retrieved at all? If so, are the results of only the last execution available?