Can we measure the “absolute” velocity of an object, in an absolute reference frame? Can we define the velocity without choosing an arbitrary reference frame?

If yes, where is this “absolute” reference frame?

If not (as I think it is): we know that time and mass is depend on speed… then how can we estimate the age of the universe, as there is no absolute reference frame and therefore no absolute time? Also, when our mass is minimal, it shouldn’t mean that our velocity is also minimal? The mass is not dependent on the reference frame, right? I cannot loose 10kg by changing the reference frame?!

Please, help a confuse non-physicist.

Bonus questions: Do you understand my questions? Do they make sense?