As mentioned earlier when the ACT App is used CAESES only acts as a parametric geometry provider for ANSYS Workbench. Hence you cannot benefit from the CAESES optimization tools but have to rely on the ANSYS Optimization/ANSYS optiSLang.
The connections among the ANSYS tools within Workbench is quite straightforward by just linking the related components however you would have some little issue when you would like to include some non-ANSYS tools unless you write your own app.
When you use CAESES Software Connector, you have the capability to link every tool, in case they support scripting.
Coming to your questions;
1) You have to keep in mind that when you are running an optimization/DoE, each time a new design folder is created including the files in your Software Connector.
So let's say CAESES is working on the design# 142. The CAD geometry and all the scripts related need to be located to the specific folder.
The scripts where your local path is mentioned has to be made dynamic by getResultsDir()/getDesignDir(), etc.. so that each time CAESES copies the script file to the new design folder, the paths are updated.
You do not have to make the ANSYS installation path as dynamic since it does not change from design to design. But sometimes is useful when you would like to use your CAESES project on another computer. So by just changing once the path you will be able to update your script on several locations, if any.
2) As mentioned on item 1, as a must you have to update your relative paths. Do not forget that the way CAESES links the Softwares is through scripts. The Computer or the Softwares would not know where the files they are looking for are unless it is explicitly mentioned within the scripts.
3) You just would need one script/journal file for ICEM CFD that includes all the commands necessary to build your mesh. You can create the necessary file within ICEM CFD automatically.
4) *.bat file is a windows batch file containing windows/dos commands however *.sh file is a unix shell script file that contains a series of unix commands.
If your operating system is Windows, your main batch file that includes all the commands to run the tools should be a *.bat file. And in the case of Linux, it should be *.sh.
5) Within the menu of your optimization engine, you can include your desired objective functions under Evaluations.