It takes time Google to detect the changes.Do you have made the redirects to all those old pages and submit the new website pages to search CONSOLE?do THAT FIRST.

If you cover every aspect then word count of 4000 will suffice.Use LSI keywords and use original images,your original video review of the product.Don't use stock images.

I just to use Nitropack for free wordpress.It is free for upto 5000 traffic for month.It will suffice for all your Needs.Also increase the website speed.

canonical tag is the best option and

Hello, Along with this,I Suggest to build some fresh links regarding this.For example 5 links from High DA websites each day for 7 days.Also please if any single page is indexed then interlink each other.It will help in indexing.