Did UAE's Al-Amal (Hope) Emirates Mars Mission (EMM) launch directly into an interplanetary trajectory or did it spend some time in LEO?

What was the duration of the launch window this day?

According to Spacelaunchnow, the daily launch window was instantaneous, but there were daily opportunities from July 15 to August 12.

Did it first enter a short period of LEO for phasing and/or staging, or did it launch directly into its interplanetary trajectory?

From the timeline, it appears that it did about a half-orbit between second-stage first cutoff (SECO-1) (orbital insertion) at T+0:11:21 and second-stage second burn (trans-Martian injection) forty-five minutes later at T+0:56:39. (As a rule of thumb, the period of circular low Earth orbit is a little over 90 minutes, so 45 minutes between the two events means about half an orbit).

T-0:00:00:   Liftoff
T+0:01:31:   SRB-A Burnout
T+0:01:46:   SRB-A Jettison
T+0:04:06:   Payload Fairing Jettison
T+0:06:34:   MECO
T+0:06:42:   Stage Separation
T+0:06:52:   Second Stage Ignition 1
T+0:11:21:   SECO 1
T+0:56:39:   Second Stage Ignition 2
T+1:00:33:   SECO 2
T+1:01:34:   Hope Separation

How many stages were involved?

The H-IIA uses two hydrogen-oxygen core stages, plus solid rocket boosters. The first core stage is ignited at liftoff.