I've maintained a blog and help a friend who owns a business promote on Facebook.
Both are in French.
>- Lack of clarity about SEO rules in this regard. Eg: Will Spanish content rank higher than english one if I search in spanish? Or will google do a combined (transliterated) search and rank the best?
In my experience, it will rank higher. My blog had one post (how to get a debit card from a certain bank). It was a few years ago and people are still commenting on it (I think 1000 comments). When it was self hosted, it was ranked higher than the bank itself for the combination (card + bank name + country) if I recall correctly.
The important thing is that it was comprehensive enough so the bloggers, geeks, members of different forums in the country started sharing this link, calling it a "gift", etc. I haven't done any promotion. Basically just write and forget. Content quality is a sine qua non condition.
>Top Trends show what is being searched for in english. No option to see search top trends by language . Any way around this?
* Go to Google Trends.
* Now search for any string, like "fdsfjqklm".
* The resulting will have a drop down menu with countries it didn't have on the first page.
* Choose a country.
* Remove the search string.
Or, this link. If I want what people in Spain are looking for, here: https://www.google.com/trends/explore?geo=ES
Let's say people in Venezuela:
https://www.google.com/trends/explore?geo=VE
Thailand: https://www.google.com/trends/explore?geo=TH
As you can see, it shows what people are looking and not just in English but in their native language as well. It's not what you asked for, but still not too shabby because you can think about Spanish countries and then do a search, or write a script that will do that for you for every Spanish speaking country.
>- Even if its a non-english website, what are best the practices for URLs? Should they still be in english or can we use the regional language?
You don't seem to appreciate just how good it is to have non English content:
* There are a lot of people who don't speak English in every country.
* The bang for the bug in advertising is just great. 10,000 impressions cost about $1 for the French page. Sometimes, it is so low, Facebook displays it as 0. If it were in English, all this would be lost to click farms in India, Pakistan, or Egypt. (I've had a page in English, and it was cluttered with people who would just like that page and had nothing to do with the stuff in it). So, having a page not in English is great.