On the source extractor, you can use the vacuum pump on the unit to connect to the flask. I purchased the Source Extractor and then the components through amazon like you are intending. I did buy the adapter from soure for $5 but had to add the 3/8" tubing. You could buy this at Home Depot w/ no issue.
I am not sure the Buchner filtration is better than just straining it through a filter. I have only done 1 batch and doing more research on how much can be extracted in this method.