Setting up a computer is one of my favorite things!
1. Make yourself an admin if you wish, there's no real need unless you think you'll need access someday and the kids won't give you their password!
2. No, McAfee is not "that" bad. Maybe not the best, but better than it used to be. F.W.I.W Eset isn't as good as it used to be either. You probably don't have time now, but if you watch the sales at Newegg & Fry's, (you need to create an account and sign up for emails), and they'll both send you their best sales and specials. Both McAfee & Kaspersky are free after rebate regularly.
3. Teamviewer was mentioned. In my world it's a must have! Even at home, when my wife says, "Larry, could you help me.....", I just open teamviewer on my desktop and log in to hers and help her. I also help many friends and family around the country using it. This program is free for personal use. I think as long as we don't charge for our services we're ok. I'm careful though to not abuse it.
4. Someone else mentioned backups. Do yourself a favor, download Macrium Reflect Free and put it on all your computers. In time you'll love it enough that you'll spend the money to get the paid version, I did. But really, the free version is not at all crippled. This company is head and shoulders above everyone else in this field as far as I'm concerned.
5. Use Macrium Reflect! First to do those clean images, (to include those hidden/restore partions), and then as needed. Example, on my desktop I have it scheduled to do a full backup once a week and a differential every night and let it keep 60 days of backups. That's overkill for many, and won't work for others but even if you just do manuals regularly you're ahead of the game.
If you have an image and a hard drive dies or gets hosed by ransomware or whatever, just do a restore. Then it's just a matter of logistics. You know, figuring out how to accomplish backups and restores between where you are and where they are. If you have Teamviewer & the kids have external drives with backups, no probs. Just log in, do a restore and you're good to go.
6. I recommend that you stay away from Malwarebytes. I was a user for years, then a paid subscriber for years and I've had to to take it off all my computers. It's a real mess, and it doesn't look like it's going to get any better any time soon. And no, I don't think there IS anything to substitute for it, sadly. There are some that claim to be....but they aren't.
7. I think those are the biggies. After that it's a thousand and one tweaks & fixes. There's a ton of very good free software out there depending on need. That's where all the fun stuff comes in!
Oh, and do yourself a huge favor and R.T.F.M. on Macrium & Teamviewer. There are some things you can do that can really help you out. For instance, on Teamviewer you can create an account, assign the girls computers to your account, give them distinctive names and see a pop up whenever they're logged in if you have it start with Windows. You can also use the Whitelist/Blacklist. I use the Whitelist mostly, giving only myself permission to log in.
On Macrium, you can add WinPE and then add Boot Recovery Menu Option so that you don't have to boot to recovery disk to do a restore. I only use it when I want to do a restore on mine, rest of the time I leave it off.
Anyway, these are some thoughts.
Good Luck and enjoy!
Larry