Profile: Dressmaker

I would like to update from version 1.7 to 2.0. I have a rounding problem with the current version (1.7) As soon as there is more than 1 product in the shopping cart, the order with PayPal does no longer work, because there is a difference in the total price calculated by Nopcommerce and PayPal.
Does Version 1.8 and newer really solves this problem? If so, how can I update the plug-in?
It is enough to upload the new version 2.0 via the Nopcommerce plugin management. Will this overwrite the old version overwritten and will the configuration retain? Or do I have to do it differently?
Thank you verry much.