My take from the context of the overall lyrics is that 那 is correct.
The starting line sets the basic premise for the song 足跡遍天下, (an itinerant traveler, not a sojourner)
Then you have 始終找不到吾家, (still unable to find my or rather a home for himself; the operative word here is 始終; he didn't have a home, he was searching for one)
Finally, 啊！萬千燈火透廣廈, 啊！那裏是吾家, ...
1.Is it possible that Sam Hui like many Chinese use 那 and 哪 interchangeably? I was one of the guilt one, I always wrote "那里?" instead of "哪里?"
Nope, at least for nowaday mainland Chinese, we do not do that. It is definitely a typo.
2.Is it possible that "那里是吾家"(there is my home) was intended to be "哪里是吾家?" (where is my home?)?
Possibly, based on the ...
The following may be folk etymology. More research is needed - specifically, textual evidence of when「正斗」started being in use among the general public.
「正斗」originated as a term in initiation rituals of Chinese secret societies or criminal underworld groups. The details of the ritual vary from source to source, but the ritual is said to involve a wooden ...
"睇下我嘅" (Taei har ngo gea)
"take a look at mine"
It is definitely colloquial Cantonese.
These kinds of "rough" phrases are usually meant to indicate something to boast or show off or a demeaning comparison, like, "pay attention, you might learn something"; "this is how I would do it"; "you see those biceps?"
This phrase therefore has to be a follow-on ...
「睇下」means 'take a look'
「我嘅」means 'my (thing)'
Kim is most probably a person's name. So I presume Kim is the one leaving the note.
The whole sentence means "Take a look at mine!" Kim is probably trying to show you something. (If that note is for you.)
No, it doesn't mean 'I am generous.'