Dylanspiritwind,

Welcome toi Justlinux!

In answering your questions

(1) All information are stored in binary bits of either "1" or "0" on a hard disk so the filing system and the operating system is immaterial. In your case you can do either because one of them is your backup so you can do whatever you want even damage the second disk without any consequence to your original system. Thus it may be easier to have two ext3 disks before proceeding to turn one of them into the xfs filing system.

(2) The answer is yes but it is a lot easier and quicker to use Ubuntu to do it in terminal mode. The details are available in this thread. Forgive me if I do not repeat them here. Just follow the suggestion to put Grub into a pen drive. If you don't want to read it I believe if you insert the sd card and it is recognised as device sdb1 then the Bash terminal command
Code:
grubinstall /dev/sdb1
should be able to achieve the same but I am not sure if it wipes away the existing data in the SD card.

Migrating Linux is easier than cloning it and you can do it with itself but the safe way is always booting up a Live CD leaving the original system dormant so that its system files are not in active use.

Key steps are (let us know if you need the missing commands)

(a) Do it one partition at a time.

(b) Just create and format another target partition of any size and any filing type (same filing type is always the best).

(c) Mount both source and target partition. (assuming the source is /dev/sda3 mounted on /mnt/sda3 and target /dev/sdc3 mounted on /mnt/sdc3)

(d) Change directory to the source /mnt/sda3 (not mandatory but the command below is written assuming you do it) and then copy the entire filing system across by command
Code:
tar cf - . | (cd /mnt/sdc3; tar xf -)
(e) Do whatever necessary to update /etc/fstab to point to the new target partition by keeping or removing the source partition.

(f) As a rule duplicating a file system using a "copying" command does not copy the boot sector and so the boot loader must be updated separately. dd is the only command that includes the boot sector.