on studying the latest pattern that websites are following is PAGE or Site redirection. Yes, it is beneficial to avoid 404 errors in the web sites. as larger the amount of google 404 errors the site ranking is likely to do down.. still need to discuss what are the best approaches for redirecting!! applying 301 redirection code in Htaccess or to use PHP redirection??
.htaccess is best for 301 or 302 SEO friendly redirection. You will get the code for it on Google. FYI.. 301 is used for permanent redirection whereas 302 is for temporary.
You can use php or httacces, actually it depends on you. Personally, I use more often the second one. Don't use a 301 redirection for SEO because you can get hurt.
If you have to make redirect few pages then you can use 301 redirection through .htaccess, but if you have to redirect a number of pages, then you should use php method
301 and 302, both are SEO friendly. If you use 301 for redirection, the new page gets all the credits of old page because it is permanent redirection whereas in 302 redirection, new page do not get any credit of old.
It's recommended to use 301 redirection but don't have too many like more than 10. Just go to cpanel and set them up quickly. Do use them only if you really need to, if you can change the page content manually or delete page it's better than 301. 301 is used for instance if the page is already receiving a lot of traffic (so deleting it isn't advisable), or if it already has many backlinks and you're optimizing the page...
Yes, It would be better to optimize the page to make SEO friendly then to redirect them to a new page. If you want to redirect whole website to a new domain, 301 is good option.