your host probably allows you to set up redirects for any domain name you register. look in your control panel for the domain admin and then redirect the sites to whatever url you want. you can also use an HTML redirect, just google it and copy and paste the code.
301 is a good idea, 302 is a bad idea(duplicate) or a better idea, is make a one page site with slightly different content and click a link for visitor to redirect
You can 301 redirect different domains to one domain. But if you want to rank different domains high in search results; and that each high ranked domain will redirect to one domain then I guess its not possible.
You can park you domain and point them to the same website. It is possible with every hosting account.
Yes, I know and it is also possible to setup URL forwarding option for a domain, but I don't know which domains will be displayed by google if I have several domains for 1 web site and what is google's attitude to this matter?