Our HC has always said that if you can land one foot on the beam on a cartwheel, then you can land both of them

To PRACTICE... just hold the second foot in the air for the split second needed to place it on the beam.
As for handstand... you need to kick up higher... which means you need to know that you can safely get out of the handstand (in case you kick too high)...
HS-Forward roll on a floor line... then a floor beam... then a low beam... etc.
I used to do a HS to a bridge on beam when I was younger.
You can also practice kicking up to a handstand at the end of the low beam with a wedge mat up against it... or with the beam against a padded wall.
Good luck.