Help Wifi Tethering and rooting

I'm looking at Metro PCS for tethering a cell phone to my home PC. The phone will serve no other purpose and will "never" be used other than for tethering. Metro seems to have a few Samsung phones for little money that I am considering. Is anyone here using their phone in this fashion? I want to root it so I can get rid of all the apps that I'll never be using. Since it will only connect my PC to the net, will the rooted phone be pretty much safe from any hacking? I have a few phones to list if that helps, Galaxy J3 Prime, ON5, J7 Prime and a few LG's, Arosto, K7, Stylo 2 Plus. Prices are cheap, so if I break the phone I won't be hurting over the loss. Any advice on rooting (backup the system first?) and apps to get before I root it so I can have more control over the phone?