Queries about custom ship style

Hey y'all, I've been getting sick and fed up with all my custom races having the same ships as the main races, so I was thinking about trying to make custom ship styles for them. I had a look at the ship style creation thingy in custom race and came up with these two questions.

1. Do I need to create multiple ships for each size of hull or can the AI deal with just one?

2. Do I need to put anything on the ships? or will the AI appropriatly assign components (weapons, engines etc.)

I was gonna see if I could get these questions answered first before I went on a massive ship creation spree as my time is a bit tight atm

any help muchly appreciated!