Yes, go into your network adapter settings thru Networking or thru Device Manager and find the network adapter. Double click and an adapter should show, right click, and go to properties. Then, go to the advanced tab. Go to speed and duplex and change from auto negotiation to some other Full Deplex like 100Mbs or 10Mbs.
You can also turn off iPv6 if you are having problems. Ipv6 is worthless unless you're using Windows Home Group. Let me know.
That's not going to do anything. I'm assuming you're referring to BW to the Internet? If so, there are HW products you'd need where you can define BW limits to/from certain networks/hosts. I don't know of any SW products that you may be able to use.
Changing your adapter settings on one side of the connection is only going to give you problems, not to mention that if your service is, say, only 10Mb down, then it's still 100% of available bandwidth. Unless you can force the switch or router that you're connected to to the same setting, leave all your PCs to auto.