Alpha Glint

Alpha Glint
Not usable in combat with an ally or an older vampire.
if Strike: combat ends.
IF Only usable before range is determined. Combat ends.

If player A is acting, and before range he has first oportunity to play cards, and hr played Alpha Glint, does it fire rightaway ending combat before any other player is able to play cards?

if not, when card effect occure in such situations? 

If Alpha Glint is played during pre-range, combat ends. You move to the "end of round" steps where Taste of Vitae, Psyche!, and other cards are played. The other Methuselah has a chance to play cards, but after Alpha Glint is played, we're in a different part of combat, so the other Methuselah is limited in what cards they can play.

That's mean alfter Alpha Glint players go immediately to end of combat step, so there is no chance for other players to play for example Outside the Hourglass?

Correct.

What if the acting player played Domain of Evernight for aggravaded damage and played Outside of Hourglass before Alpha Glint?
1. We still move to "end combat".
2. Hourglass inflicts aggravated damage and there is even no opportunity to play Alpha Glint or "not acting" player can play Alpha Glint but aggravated damage is still inflicted before Alpha Glint?
3. Any other?

You should read this thread: www.vekn.net/forum/rules-questions/76356-illusions-of-the-kindred-vs-outside-the-hourglass