The 8.1.7 error is most likely because you're running on a P4 system and the 8.1.7 installer had a bug on P4 systems. There's an easy workaround and you'll find the article easily on Metalink.
The other problems sound like you just didn't start the listener. To start the listener the first time (since I don't think Oracle creates a listener service until it is started the first time) after the installation, go to a command prompt and type "lsnrctl start" and that should then create a service in the services control panel which you can use to start/stop the listener after that point.
This was first published in August 2004