confused of carshalton

I have used Outlook fo rseveral years more or less happily until it seized up a few days ago because the pst file was too large [7.5 gigs]. I have encountered enormous difficulty in restarting it although I do seem to have managed to save the info on an external drive, Thus my questions: Can em Client 1] store all my mail on my pc 2] work with a “huge” inbox [I WANT the inbox to be huge so that I have a record of EVERYTHING with a search-facility for parsing] and 3] import my “huge” outlook inbox to keep my data in one place

the answer on all of your questions is Yes. eM Client is designed for quite large data files. It internally uses robust SQL engine and stores data that is used often separately from the other data.
We test with 15-20 gigabyte databases and the product is able to handle that.