Avraham's servant, who is not identified by name but is attributed to be Eliezer, is referred to by three different titles as far as I can see during the account of his finding Yitzchak a wife.

In order of the narrative he is described first as a servant, then as a man, then as a stranger, and finally a servant again. What is the significance of this?

I have learnt that in Sefer Yona, the sailors who take Yona on the ship are first referred to as sailors to show that they were typical sailor characters (i.e. idol worshippers, superstitous etc) but after they recognised G-d they are referred to as "men" in order to show their higher spiritual status. Is there anything like this to learn in our parsha?

the midrash explains eliezer;

he was a servant; that's why he was should not have made the condition of the camels being watered, a servant should carry out his orders as given.

he was a man; because of the bitochon he had hashem. that is why hashem fulfilled his condition (camels), even though he should not have made it. and because of the respect that lavan and the gantze mishpocho showed him because he appeared choshiv.

he was a stranger; avraham instructed yitzchok to make sure that eliezer had not touched rivka during the travel back. suffering this indignation because avraham did not trust him because he was a stranger (ger tzedek) was eliezer's greatest schus.

some things never change.