I don't know about it being an easy job. Anything that would have me on my feet that much would not be easy for me.

I'm sure that they will have the support you need for training. There will be times where you are very busy and other times it might be slow.

As for as mistakes, you're human, there will be mistakes but usually most mistakes can be taken care of by a smile, "I'm sorry" and finding a solution.

I'm sure you will do just fine. Just remember to breath. (I tend to hold my breath when starting something new.)