Learn English – Can you say “two groups of people stared at each other”

Example 1 seems to be legitimate Indian English, see

Something which Indian English has that is not found in other varieties of English is the use of only and itself to emphasize time and place. It comes from the Hindi word hi and produces sentences like "I was in Toledo only" and "Can we meet tomorrow itself?"

extract from language in India

More discussion on 'only' in Indian English here Dustin Freeman

Example 2 is probably Indian English too. You could say you are concentrating on that task, if you wanted to be better understood by a foreign audience.

Example 3: either is correct, I would think the 2nd is more colloquial

I don't think you be misunderstood with any of these colloquialisms. To me they are colourful additions to the language

There seems to be some evidence that as of late (in the sense of recently) was perhaps a bit more common a century or two ago, but I think including as has never been the norm. For all that, I can't really imagine a context where OP's example...

"and as of late he has agreed to return home"

...would be considered "natural", even if we removed as. The reason it doesn't work is because of late in such contexts means during the time period stretching from the present moment to the relatively recent past. That's to say, things happening of late are normally things which either take some time to complete, or which can happen repeatedly (unlike, say, a single act of agreement).

As @Edwin succinctly notes, lately/of late apply to durative (rather than "punctive") recent actions.

In OP's case, the natural phrasing would be...

"and he [has] recently agreed to return home"