Fenix 6x spring bars, screw not visible ? What about changing spring bars ?

They are more standard watch spring bars now, although more beefy and stronger spring. They have little ridges to make removal easier.  Would need to replace them with comparable pins. I have no concern with them in most use, though I didn't mind the screw bars.  With the screw bars though, you have to be sure to put loctite back on them.  

Here's what they look like now and the tool I use:

https://flic.kr/p/2hCiGY8

Pseudo-fed beat me to the answer.

While I liked the beefy pins of the Forerunner 945 and previous Fenix iterations, I've seen a few reports (not many but still a few) of the lugs breaking so my suspicion is drilling through the lugs removed enough material to make the lugs the weak point instead of the pins.

As a mentor of mine said: "it's better to break the cheaper, easier to replace part."

Given the Fenix still uses plastic lugs (the Chronos and MARQ lines being the only Garmins with metal lugs), it's a smart move for Garmin to move to these new spring pins.

A side benefit: it seems to have resulted in a smaller lug-to-lug distance, making a Fenix 6X feel more like a Fenix 5 or Forerunner 945 on the wrist.

That's for sure on the shorter lug distance, making the F6 line more "wearable". Here are a couple pics of the F3 vs F6X showing shorter lugs in 51mm models, and a pic of F6X vs F5+, showing this year's 51mm model is shorter than last year's 47mm model:

https://flic.kr/p/2hvFj2d

https://flic.kr/p/2hvFj1w

Can i use forerunner 945 band to it?

945 is compatible with 22mm quickfit bands, so you can use 945 band on the F6 47mm watch.