Addressing Problem 1 First:
First Of all you might consider - for both the sake of your user but more importantly your own -simply using the lot no. as the button, i.e. simply draw a standard square around that, they sort of look ugly anyway because they go inverted but it's up to you i suppose - don't waste to much time on it, trust me you'll have much more stuff to waste your time on . This way the user will always know to click on the lot no. to be taken to the record in question.
Secondly
Yes, when importing you can choose various match fields (as many as you want) in your case it would seem a lot no. and perhaps a suburb or estate name would suffice seeing as your getting the data externally from somewhere and don't have a primary key available at the other end (from what i'm guessing).
Anyway, any questions, yell
~Genx