Hi,
1. Use EPMSelectMember in template to select members based on property filter and hide context. I don't think you can filter context based on BPF parameters.
2. Using Excel advanced options you can hide formula bar and Headers. Once you are done with required settings of excel options Protect template using EPM-Sheet Options-->Protection .
But you can not hide EPM related options like Refresh and Save data using standard settings.
3.Macros are mostly EPM version based ( MSOffice Excel up to 2007). If you save your xlm template in one version of EPM Add-n for example SP13 then who ever is trying to access the same template should also at the same level of EPM add-in . But I am not sure about latest version of EPM Add-in, whether is there any improvement related to version compatibility of macro templates or not.
Excel 2010 is more stable in case of using xlm templates.
Thanks,
Raju