ISPs don't care, actually. They care about operational problems, but you serving a constant stream of web traffic is probably not going to matter to them; web traffic for even a pretty successful blog is going to be a tiny volume compared to you streaming 4k movies from Netflix.
ISPs will have rules (maximum data volume per month) and restrictions (ISP equipment auto-drops all sending/receiving packets on port 25, 80, 443, or 456), but within those limits the ISPs do not care as long as you cause no problems for them.
Also, one of the easiest ways to expose e.g. port 80 of your in-house server is to just have your local server do an SSH port-forward to a remote server like a cheap VPS. Note that by default it'll bind to a localhost port on the remote, so on the remote you'd need to have an HTTP server reverse proxying to the remote localhost:8080, or you need to enable `GatewayPorts: yes` in sshd on the remote. Assuming you turn on GatewayPorts on remote.example.com, here's how you could expose port 80 of localhost:
# Run this on in-your-house-computer to allow folks on public internet to visit
# remote.example.com:80 but have the traffic served by in-your-house-computer:80
ssh -R :80:localhost:80 username@remote.example.com
You can make the above connection permanent by setting up `autossh` on in-your-house-computer.
Cause the server in your house is a lot cheaper to upgrade with more RAM/storage than a VPS. By using a VPS as just a way to make traffic available, you can choose an extremely cheap VPS. It's pretty easy to find places that'll charge you $2 USD/month for a tiny VPS with 1TB monthly data transfer allowances; for $5 you can get unlimited data transfer. There's tons of good deals.
Yes, with asterisks. If you're serving static files from your house, the risk of having your server taken over is incredibly low. If you're hosting Wordpress on your home server, that risk spikes massively. So make sure you understand what is and is not dangerous, and of course, only expose the "low risk parts" to the outside world.
ISPs will have rules (maximum data volume per month) and restrictions (ISP equipment auto-drops all sending/receiving packets on port 25, 80, 443, or 456), but within those limits the ISPs do not care as long as you cause no problems for them.
Also, one of the easiest ways to expose e.g. port 80 of your in-house server is to just have your local server do an SSH port-forward to a remote server like a cheap VPS. Note that by default it'll bind to a localhost port on the remote, so on the remote you'd need to have an HTTP server reverse proxying to the remote localhost:8080, or you need to enable `GatewayPorts: yes` in sshd on the remote. Assuming you turn on GatewayPorts on remote.example.com, here's how you could expose port 80 of localhost:
You can make the above connection permanent by setting up `autossh` on in-your-house-computer.