Just getting started and read the books

I have a new Jet Mini and a few kits and turning tools and am basically
ready to try this out.  I have sat down and read two different books and
think I have the basics but I still have a few questions if its alright.

First, squaring the ends of the blanks, can I get this done effectively with
my sanding station or do I need to buy a barrel trimming tool for the drill
press?  Second, I didn't find anything that says approximately what speeds
the different operations require.  I'm only assuming that you start off with
the slowest speed until you get a cylinder?  Lastly, I have one mandrel with
five bushings - I'm assuming it's 7mm but it doesn't say - do I need more
mandrels?  Thanks for any input.

Don