your formula would something like:
if {table.field} = something then
"xxxx"
else if {table.field} = somethingElse then
"yyyy"
Crystal reports will display the last string 'displayed' in a formula. You can contenate / convert / do what you want.
your 2nd request would be something like:
totext({?start}, "MM/dd/yyyy") + " - " + totext ({?end}, "MM/dd/yyyy")
HTH