Key and Camera Questions

I don't know if these are dumb questions or not, but those seem to be the kind I specialize in.
1. If I make a key to a gate, for example, I assume I need to keep it in my inventory so I can unlock it when I need it? What happens if I get knocked out and my inventory gets cleaned out. How can I open the gate then?
2. I play on a laptop, so there is no middle mouse wheel. I can't get the camera to change vantage points, except once in a while by accident. Am I missing a trick here?
1. If I make a key to a gate, for example, I assume I need to keep it in my inventory so I can unlock it when I need it? What happens if I get knocked out and my inventory gets cleaned out. How can I open the gate then?
2. I play on a laptop, so there is no middle mouse wheel. I can't get the camera to change vantage points, except once in a while by accident. Am I missing a trick here?