Samsung S5 WEP issues and getting 5.1.X

[wampa88]

I just bought a used Sprint Samsung Galaxy S5. I have 2 questions here:

1. My router is setup with WEP (yeah i know thats old) 128 bit so i have a 26 hexdec key. The S5 will not connect to my router because the S5 will not let me enter more than 13 characters. I also have an AT&T Galaxy Note 4 that connects to my router with no problem, i can enter the entire 26 character key. Is there any fix to this?

2. I don't actually have sprint service so i wont be able to get the update via OTA from Sprint, can i get this update or do i need to root my device first?

Thanks in advance!