Considering they offer that service themselves, it would be hypocritical of them to penalize you for doing it. The hreflang tag would also protect you from having those pages marked as spam since you are telling G "Page a the exact same as page å, just in a different language" - avoiding "duplicate" content

The problem with using a software to translate your content is that it will never be perfect. There will be many grammatical and/or vocabulary errors that would decrease the quality of the content. I'm not sure if Google is able to understand content quality in other languages, but a worse user experience usually leads to worse rankings. Ideal situation, you would have those pages manually translated (but I know it will cost a fortune).

In case you decide to auto translate, be sure to use the rel="alternative" hreflang="x" tag in order to tell Google that you have multiple pages with the same content, except in different languages.

I don't think you should worry about a sudden influx of pages. Ideally, you'd drip feed them in to take advantage of the freshness factor, but you shouldn't be penalized for creating a lot of new pages.

Google won't think it's shady... they recently released a video that says they follow multiple redirects (but if you have too many, it will reflect poorly).

Why get rid of a redirect at all? I would set a canonical url as well as keep the 301 redirect.

Not sure, sorry. From experience though, 500 errors are commonly caused by the wrong permissions. Make sure you CHMOD your feed to 777 and see if it works.

If it does, try 644 (reducing permissions for security).

If not, are you using a CMS? -post in their troubleshooting forums

Common consensus: 301 redirects will drop your rankings for ~ 2 weeks but you should bounce back in rankings after then. You do lose a small amount of link juice but if the word "guides" is a common search term for your widget queries, it might be worth the move.

In addition, I would review the backlinks you currently have, sort out the most powerful backlinks, and contact the respective webmasters to change the URL to the new address and avoid the redirect.

Conversion rate = Conversions / Visitors (you had it flipped around)

Choosing whether to track unique or not depends on the buying cycle - some items (think high cost, high research) are never converted on a unique visit so by tracking unique visitors, your conversion rate is 0%.

The best solution is to track conversion per recurring visitor (e.g. conversions / unique, conv / 1st return, conv / 2nd return, etc). This will give you a better example of how many visits per conversion on average it takes for someone to convert and you can try to improve the rate at each stage.