How can I fix SEO and coding issues on my new website?

[EssentialTac]

We have a new website.  We use the "dawn" theme for our store and are dealing with a lot of issues.  Our Google & Bing Search Console is a mess with a lot of errors.  We are looking for someone to fix some coding issues to help with SEO.

For example:

1) Google shows we have 20,000+ unindexed pages because of canonical errors.  We think we fixed this but not sure.

2) Bing shows our HTML size is too long and needs to be shortened.

3) There appears to be issues with our H1, H2 containing conflicting sizing.

4) We would like the IndexNow coding to be applied to the site.

5) The theme we use switches from image #1 to image #2 when the curser hovers over the picture.  On the main page of the website, the meta image description for the 2nd image is not showing up.  A quick coding fix for a HTML guru.

6) We'd like someone to check out our search console profiles on Google & Bing.  For example on Google we really don't know if we have it set up right and don't believe the site is being properly indexed.

We know just enough to sound like we are intelligent when it comes to coding and SEO but need someone who can assist with these issues.

If anyone can throw out some quotes please send a private message.