Removing car battery for about an hour without losing radio code

Hello,

I am planning on removing my Fabia 1.2htp battery to clean underneath the tray as it’s absolutely covered with grease, and to check the power steering fluid while I'm there. I reckon it will take me about an hour. My understanding is the car only stores the settings for the radio for about 30 mins.

My question is:

(1)     would it make a difference if I reconnect the battery before the 30mins is up, and disconnect again.

(2)   Is it safe enough to connect the battery from the floor using a jump lead?

I understand some the safety precautions with short circuits etc. 

Thanks