Since the airport's renovation in 2009, both national and internations flights are handled in the same terminal building, which is not particularly large (about 150x250m). So you won't waste much time walking, and unless there are huge queues or your arrival is delayed, a 1:15 layover time should be sufficient (but not generous) even if you have to pick up your luggage.
It seems that if company is the same then they move my luggage by themselves. Am I right?
If it's a single ticket, then the luggage is nearly always checked through to the final destination. Even if you bought the tickets separately, this should be possible if it's the same airline. Ask the airline employee at the counter when you're checking in.