Hm, well I managed to fix problem #2 heh. And apparently problem #1
was because I had the absolute path in quotes. As soon as I got
rid of those it started working (although I still think it's strange since
quotes around file path names i thought was syntactically correct..and
sometimes even necessary when the filepath has spaces).

Well, if anyone out there was having the same problem as me, here is how
I fixed it:

Dim XLapp As Excel.Application
Set XLapp = New Excel.Application
Dim WB As Excel.Workbook
Dim WB2 As Excel.Workbook
Set WB = XLapp.Workbooks.Open(foo.xls) ' file that has the macro that i want to execute
Set WB2 = XLapp.Workbooks.Open(file.xls) ' xls file that i want the macro to operate on
XLapp.Run "foo.xls!" & macro_name ' Note the exclamation point after foo.xls

' After everything is over let's clean up
WB.Close False
WB2.Close False
XLapp.Quit
Set WB = Nothing
Set WB2 = Nothing
Set XLapp = Nothing