Safety first before building a farm

[Sananov]

Hello fellow miners!

With the rapid rise of cryptocurrencies, I too have decided to jump on the fast moving train of BTC farming. Understandably, before doing so, I'm gathering as much information as possible from anywhere, and so my search has brought me here. With a few answers, I might get a small farm of s9 antminers running in the near future.
Before getting into hardware and reliable storage to run those machines, I'd like to figure out a few software things:
1) Wallets- I found myself 2 which I'll be using as cold and hot wallets, but I can't seem to grasp the concept of "backing it up". If I back up my picture library, I realize that in a situation of hardware failure I can restore them to the moment of backup. However with wallets.. what exactly am I backing up? If it gets hacked/stolen, I don't assume I get my savings back since that intruder will certainly just send it to his own funds.
Atm I see it only as a safe mechanism for when I lose or damage my computer/phone where the wallet is kept on, so by downloading the wallet again, i can restore it with the file I've backed up. Would someone be able to elaborate on that?
2) Say I'm interested in running 10 S9's with their PSUs in place, what additional equipment would I be needing? Internet cables which support highest mbs speeds or a 100mbs+ speed ones are ok? Switches, obviously, to extend router to all 10 miners <-- should I look into any specific ones with unlimited speed throughput or, again, 100mbs will do?
3) Am I in need of some antivirus programs or firewall software/hardware that I keep hearing about on Youtube/blogs. Many recommend expensive firewalls, yet couontless posts say bitcoin network is safe.
4) With the 10 miners I'm planning on purchasing, equalling in 140TH/s, would it be more profitable to mine solo or in pools? And depending on the answer, is there a mining software specific for each mining style?
5) I'm currently using THIS ROI calculator. The question is- ragardless of BTC price fluctuations, is that calculation based on me mining solo or in a pool, excluding any pool's commissions atm. In other words, am I actually going to mine 0.03963 BTC/day or is it all just luck based wether I get to solve the block or not?

Thank You in advance for any answers to come. I'll be closely monitoring this topic for any new information and hopefully it helps more people in the future.

[odolvlobo]

1. Backing up a wallet ensures that if the wallet is lost or destroyed, you can restore it. It does not protect you from being hacked. Most wallets use a "seed", and that is what must be backed up, but each wallet is different.

2. You will need all the normal stuff used to set up a LAN connected to the internet. Bandwidth requirements are not high. You will need cooling equipment.

3. While the bitcoin network is safe, your mining operation could be a target. You must assume that somebody is going to try to hack into your network, steal your bitcoins, and redirect your miners to their own account.

4. Whether you go solo or join a pool really depends on how often you want to get paid. In a pool, you get bitcoins every time the pool finds a block, while if you go solo you get paid every time you find a block. The result is about the same in the end, except that the pool takes a cut. At the current difficulty, 140 TH/s will average 1 block every 328 days. I recommend joining a pool.

5. Don't use that calculator. The problem with that calculator is that it doesn't consider a rising difficulty value, so it is only accurate for 2 weeks at most. The Bitcoin Wisdom Mining Calculator is much better for long term calculations.