General consensus is that it is still usually indexed/ranked but the value is diminished (and they may be going in the direction of completely ignoring it). See this post: https://www.seroundtable.com/google-hidden-tab-content-seo-19489.html

You can post to reddit without using imgur. Instead, post it on your website along with supplementary content, make sure the page loads fast and isn't spammy, and post that to reddit instead.

Imgur is it's own separate entity that people browse through. The main advantage imgur has is that images are "more compatible" with reddit (in terms of plugins that make loading an image easier, people are more likely to click/view because they know its a good experience).

To add some info... if you want infinite scrolling + paginated pages, check out Google's demo.

1. Yes, use 301 instead of 302. 301 would pass any authority (i.e. any backlinks) that the vanity URL gains to the actual page whereas a 302 doesn't.

2. Add a canonical URL to www.clientdomain.com/xyzpage so that search engines only index 1 version of the page

That should do it!

use #2 if search engines can see the content that would be on the other pages. if they can't see it, then use rel=next/prev

If the paginated pages still exist (and can be indexed) but you want to load more products dynamically, without changing the URL, using rel=next/prev would work fine.

"Spanish Language but Google crawls it on English"

I think this is a problem. Google should have both Spanish and English versions crawled and indexed, and then you redirect to their new respective versions.

I'd say redirect english -> english, spanish -> spanish and work to resolve the larger issue.

When did you set up the /folder/ property? I've used this to get more detailed backlink reports (as the "links to site report" is different when you enter a subfolder). What data are you looking to get?