Password excel for admin (to modify), password for only reading

Yes, but I'm not sure it was implemented in 2007. See this article to see how to save a workbook with one password required to open, another required to modify. The article only mentions 2010 and 2013.

https://support.office.com/en-in/art...a-1931257c1517

If this doesn't work for you, then you could save the workbook with one password required to open, then protect all worksheets and require another password to unprotect them for modification.