Hi groovee, Sorry for the delay answering some of your questions, lots going on!
Re the Javascript, it’d be worth you taking a look at Motoko for your backend code, it’s designed specifically for the Internet Computer and has features to help you build apps very easily. It also has strong type checking which will help you as you build. If you know Javascript already then Motoko should feel reasonably familiar, you should be able to pick it up quickly. I’d try the quick start here and see how you get on: https://sdk.dfinity.org/docs/quickstart/quickstart.html
There are some simple tutorials in here too: https://sdk.dfinity.org/docs/developers-guide/tutorials-intro.html . Your Javascript skills will actually come in handy for the frontend, so they’re certainly not wasted!
Re the node hosting, this is a similar situation to your smartphone question and currently the machines hosting nodes are in dedicated datacenters, there could be reasonable scope for smaller professional setups if they meet the hardware requirements but it wouldn’t be an at home/dynamic IP situation: https://forum.dfinity.org/t/harnessing-smartphones-to-host-dfinity/1284/4
Re GPUs, nodes aren’t currently using the GPU but this is being looked at.
It’d certainly be worth giving the Motoko tutorials a try, it would be good to know how you get on and if there are any particular areas you need help with. It’s all designed to be very approachable. Let us know what you think…