Yes, we are taught in school to try to avoid using "semantically weak" verbs like have with objects that express the main idea, like have a population. It is better if you can use a more specific or vivid verb like live. http://en.wikipedia.org/wiki/Light_verb
No. The word order isn't what we'd use, and "live" plus "inhabitants" is redundant, since to inhabit a place is to live in it.
We'd say one of the following: Turkey has about 70 million inhabitants.
About 70 million people live in Turkey.
The population of Turkey is about 70 million.