Worksheet Referencing And Position Recognition

I have a bit of a complicated one here so I have attached my book, its probably easier to undertstand the query by looking at the book. Hopefully somebody can help me out here.

I have 2 worksheets:

A results worksheet - this contains all category of results, each category has been given a specific sort id.

A foreign worksheet - this contains all categories found on the results worksheet with sort id = 7.

Now the complicated bit. The whole exercise is too pick up the correct exchange rate for the foreign category (sort id 7). each foreign type has a specific number at the end of its description in brackets e.g (3).

At the bottom of the "results worksheet" is a key which says what type of exchange rate to use for this type e.g. (3) Price of CAD 22.9 converted using exchange rate of CAD 1.9645 = £1.

What I need to do is on the foreign worksheet, it to recognise the number in the item description, keep it in mind then switch over to the "results worksheet" find the keys at the bottom of the page (the key is not necessarily in the same place all the time!!), match the number in the items description with the corresponding key and then find the exchange rate.

As i said very difficult to explain, since I reletively zero experience with this kind of work in excel. Luckily I been muddling my way through a work project gradually thanks to a forum member here. so i hope we can keep this up!

edit:
two restrictions in the way this solution can be done:
1- Results worksheet can not be modified, but it can be referenced to using INDIRECT, and you can make any number of modifications outside of the results worksheet.
2. Any solution must be automatic.
/edit

I have attached my workbook and highlighted the bits I need to fill and the picks I need to pick up.

Would be ever so grateful if some1 could show me the light here.