SEO questions from an Expert

Hey all,
A client of mine had their page checked by an SEO expert, and there are some points I do not know how to answer. Can anyone help me, please?

1. Non-shalsh URLs: If you have both versions and both versions are indexed with a search engine, you will have duplicated content. URLs do redirect, but using a 308 redirect, it should be 301. I've contacted Squarespace Support about this, but they say they do not know about this redirect. Can anyone help me understand this?

2. URLs contain meta robots for the relevant pages - However, tag pages are indexed (even when blocked with robots). No index tags should be no-index, same with blog category URLs. This one is also a bit of an enigma. If anyone can help me understand, I would greatly appreciate it.

3. URLs do not redirect when a cap is added to the URL slug. Ideally, it should be 301 back. Is there a way to automatise this? Squarespace automatically changes all slugs into lowercase, but as the client works with people with disabilities, they may enter a URL with some capitalisation. Is it possible to automatically get those URLs to redirect to the correct one without going to the 404 page or manually create URL mapping?

Any help is appreciated. Thank you!!