Cuttlebug and shims

I received a Cuttlebug for Christmas - super happy because I had been umming and ahhing about buying a die cutter since starting scrapbooking a few years ago.

My MIL gifted it to me and she mentioned I might need 'shims' with it - she has a stack of papers she puts through her machine to get the die to cut.

I wanted to buy something specific to use as a shim rather than having to have papers lying around. So I bought a magnetic sheet and rubber mat shim set from eBay advertised for the cuttlebug.

I have a few questions - and for reference the only dies I've used so far are Studio Calico dies.

I use the A plate + B plate + magnetic sheet, paper, die + rubber mat + B plate + a piece of cork

Some images online show the rubber mat being on top of the die but my die has left a hefty mark in the rubber mat, that I worry could cut through eventually. I wonder if I should use the rubber mat on top of a B plate?

I guess I am thinking out loud, and wondering what a good combination of shims + plates would be. What do you guys use?

It also seems crazy to me that you have to use stacks of paper to get it to go through the machine and why Cuttlebug doesn't provide all of the bits you need to cut from the beginning? Is it normal to use lots of shims?

Any advice gratefully recieved.