The Sia-UI folder contains more than just the blockchain. For me it is 7.4 GB because I am also uploading a lot and my wallet file is large (old wallet with thousands of addresses). On a fresh install this is going to be way smaller. The 7 GB on your PC sounds about right.
Originally I think I was hosting 12 contracts and then each time I close and open the application, the indication of the # of contracts keeps going up by that number. But I think the hosting of those original contracts is still valid. Not sure if this answers your question.
I have just updated the blog post to reflect a change to the API - 'minimumXXX' is now 'minXXX'. These commands were changed when we upgraded to v1.0.0, but the blog post was never updated to reflect that.
minuploadbandwidthprice, minstorageprice, and mindownloadbandwidthprice are now the correct settings.