Yes, in ANSYS ACP, the model you are using should be designed from Mechanical Model and the structure first designed before sending it to ANSYS ACP. You can then mesh it depending on how you want it, based on element size or mesh divisions. As regards selecting the solid elements, you can do so from solutions in ANSYS ACP post. As regards if there any option to do mesh refinement in  thickness direction for composites, yes there is. You can define it in fibre direction or not, using the Rosette on the element (I hope that helps, however, your question seems a bit moduled up)- See attached figure if it helps