[Need Help] SILO Structure on WordPress and SEO Effect

I want to develop SILO structure on my old website. There are 25-30 blog posts on this site.

Is it necessary to redirect the old page links to the new links? I am confused on thinking about duplicate content issue. (I don't need any SEO benefit from the existing backlinks of the old posts. I planned to build fresh links for these pages.)

If it is necessary to redirect, which plugin is good for this? and how long should I keep the redirect? (Actually, I don't like to keep unnecessary plugins)

Should I do anything else on Google Webmaster Tool?

Thanks in advance.

Not strictly necessary, but I'd definitely be redirecting the old URLs. I've used 'Redirection' with good success. It allows you to see the stats on how often the old URLs are visited, which will also help you monitor which are still in use. Once they all stop receiving hits, you can remove the plugin. Alternatively, you could set the redirects at server level; meaning you wouldn't need to install any plugins at all.

I Can help you out with the SILO. DM