you don't
have to use late binding, it is just considered the better option to cater for a changing environment - as discussed in the links. Google some more to get more opinions. If you have the right references at the moment, then it is not a problem at the moment.
With regards adding code to handle all issues, that depends on the code you already have. You have mention pdf, that is handled differently from 2007 so you need to make changes there - google 'access 2003 v 2007' or similar to find out what other changes are required
here is a link to get you started
https://technet.microsoft.com/en-gb/library/ee523661(v=office.14).aspx
You may find you are not using any of these features so it won't matter or that there is backward compatibility so again, no changes required.
Your issues are:
Since the roll out, users are unable to analyse reports in Excel or PDF it or snapshot it.
we have eliminated references as an issue for excel, explained about pdf and I believe snapshot disappeared in 2007 in favour of the new pdf output feature as well.
I don't understand what you mean by 'analyse reports in Excel', a report is basically a 'paper format' style of presentation whereas I suspect you mean you are either exporting a query to excel or using excel to interrogate access - perhaps you are using a feature there which has been changed for 2007 or the problem is with Excel rather than Access.
Perhaps you are using shortcut menus to print to pdf or whatever - these also have changed from 2003 to 2007.
Without knowing your code I could keep guessing.
Other basics - I presume each user has their own front end on citrix and excel is located there as well and they are not using excel on their own pc to access something in citrix?