What's the exact procedure for holding the challos in lechem mishneh. 
I'm not asking about the number of challos used or which one to cut (top / bottom) but how do we hold them :

- do we hold them with the mat or do we take it off before the beracha ?
- do we hold the challos bottom on bottom or bottom on top ?
- how exactly must we hold them to have the bottom one nearer on friday night ? by leaning them ? 
- does both hands must touch both challos or the right hand grab one and the left the other ?
- after the beracha do we move apart on the table the one we don't cut and only grasp the one we're cutting ?

Thanks for your help