Downgrading /upgrading Mi Note Rom

Jan 23, 2015
hi i wil get my hands on a brand new mi note in a week from now. I'm considering replacing the pre installed stock rom version V6.7.1.0.KXECNCH (miui 6 china stable rom) with the multi language stable w/o rOot 5.9.10 from

1 can i just use the update app ? If no , please advice the process
2. In case i want to go back to the stock rom miui 6 can i just repeat the process 1 or this will turn my mi note into a brick?

Apologies for the probably silly questions but i'm not an experienced user and would like not to stumble in 'y footsteps.