The vast majority of the time a primary source document won't use "Ego" at all, as it's only used to emphasize the subject. So no worries there.
Ego is nominitive, and used only as the subject. In English, if you'd say "I" use "ego" in Latin. (Or don't use it at all.)
"Me" is accusative and ablative, and used as a direct object and object of a preposition. If you'd say "me" in English, use "me" in Latin.
if people still spoke roman, you could probably use that in conversation. however, duolingo probably wants you to use the literal translation so that a. they know you know the actual translation and/or b. they want you to be in the habit of answering word for word. if i were at duolingo i would probably accept that. ;)
"Male me habeo" is literally "I have myself poorly". The infinitive is "habere". It does sound a little bit like "habitare", which means "to inhabit": Romae habito--I live in Rome.
|TO HAVE||HABERE||TO INHABIT||HABITARE|
|I have||habeo||I inhabit||habito|
|you have||habes||you inhabit||habitas|
|he/she/it has||habet||he/she/it inhabits||habitat|
|we have||habemus||we inhabit||habitams|
|y'all have||habetis||y'all inhabit||habitatis|
|they have||habent||they inhabit||habitant|
The pattern you'll find in the present active indicative generally looks like this:
Please, someone explain this to me...
I was asked to translate. I feel poorly... when I wrote... Me male habeo, it was taken a a wrong answer, yet in the next exercise, duolingo wrote... male me habeo... my answer was... me male habeo, which was also uncorrect!!!
which is then the proper translation????