Did the same here, and worked perfectly. Some usernames and passwords in most apps will need to be inputed again. Other than that, it worked perfectly.
Yes. All data currently on your device will be wiped and will be replaced with your 4S data. You can attempt to inject the new texts currently on the 5S into the 4S backup before restoring the 5S with the 4S' backup using certain backup utilities.
Yes. All data currently on your device will be wiped and will be replaced with your 4S data. You can attempt to inject the new texts currently on the 5S into the 4S backup before restoring the 5S with the 4S' backup using certain backup utilities.