Buying from Bricklink

I am completely new to Bricklink and the Studio programme, however I have (stupidly) decided to makemy first model, a model of my own house. I have finished it now and it is 4350 parts, 449 lots, estimated price £663.

I would now like to try and buy it, however I have run into a few issues, so I have some questions regarding the Bricklink Store as per below.

1. No matter how many times I click show me stores that buy in Pound Sterling, it insists on showing me Euros. Any way to easily change that?

2. When it does the search of all stores worldwide, sometimes the top right hand corner says 4276/4350 assigned (98%). Does this mean that there are 74 parts that are just not available anywhere?

3. Sometimes, the assigned goes over 100%. Does this mean that I will be sent excess parts as they have been bundled in lots that are bigger than I need?

4. Following on from 2, if I buy those parts and check out, does my Wanted List update to just those 74 parts so I know which parts I am still missing?

5. All of the prices of the stores omit shipping. If I understand correctly, I go to check out with each of the stores (there are 37 stores, god help me) and wait for them all to come back with a quote for shipping, which I accept then pay?

I am finding all of this quite complicated, so any help would be greatly appreciated, thank you!