Changing all 302 (Meta Refresh) redirects to 301 redirects

Should you change thousands of meta refreshs on a site to 301 redirects?

[errorsamac]

All links on my website go through a redirect script which issues a meta refresh (302 redirect) rather than directly linking to them. Currently, the redirect script is Disallowed in robots.txt from Googlebot. However, I am afraid that might not be enough and that I should change all 302 redirects to forced 301 redirects using php scripts. So, my question to all the experts out there:

- Should a site have 302 redirects on it assuming the redirect script is Disallowed in robots.txt?
- Should all 302 redirects be changed to 301 redirects?
- Will it "hurt" if you do a massive change of all 302 redirects to 301 redirects? (Does Google think badly of sites with thousands of 301 redirects)?