Advice on how to set up external hard drives with Laptop

Hey there, bjwest1977.

Basically all of this is possible. You can easily set the power plan settings for your laptop - go to power options -> change plan settings -> change advanced power settings -> choose power buttons and lid -> lid close action -> and select "do nothing". Do this for the power plan your laptop is using when connected with the AC adapter and when you close it, the laptop will stay on and your TV should be treated as a primary monitor. This way when you select the HDMI slot from the input menu of your TV - you should see your laptop's desktop. Even though this is possible - I wouldn't choose this option if I were you. If the laptop is working 24/7, you're risking a failure, especially if it's in a cabinet (which I assume won't be very well ventilated). The generated heat won't do you any favors. Instead I'd recommend that you still change those settings, but go to BIOS and set a time when the laptop will start automatically - e.g. set it for 9AM Monday - Sunday (depending on the options you have in your BIOS). Furthermore depending on the laptop's configuration, it might generate a lot of heat when running full HD movies on your TV. E.g. I have a laptop which is 3-4 years old and have no trouble playing movies on it (its monitor has a 1366x768 resolution), but when connected to the TV (resolution 1920x1080) via an HDMI cable with the same set-up as described above - it generates quite a lot of heat while I watch movies.
You'd definitely need USB hubs with that number of HDDs and don't worry - externally powered HDDs can be connected to an externally powered USB HUB the same way as portable external drive. But note that if they are in the same cabinet, they would generate even more heat and this might lead to failures. Overall it doesn't sound like the best environment, but all of this is doable.
I though about a laptop cooling pad, but if there's no way to get cooler air in that cabinet - it will rotate the warmed up air and that's probably not a very constructive option.

Hope that helps. Please let me know if you have any questions.
Boogieman_WD