I forgot to add, SBM, you'll need snap caps if bring your own weapon. Not for any need of the laser system but, as in normal dry firing, to prevent damage to your shot gun or rifle. Just as you'd do if dry firing 'at home' in the usual manner.
There's no constraint in the cinema set up that would stop you firing from kneeling, sitthing, standing or standing off sticks. If there was height enough you could construct a 'mini' high seat to shoot from.
The deer can be also 'set' stationary, side on, front on, oblique or acute on. So again you could practice crawling in and taking a prone shot from an artificial tussock to re-create a hill stalk.
Ditto you could construct a 'mini' duck blind or even grouse butt. Heck, if you wanted, even shooting from a 4x4 driver's seating through a the passenger window for those who prefer that means of stalking.
Effectively if it fits in the room you cinema is housed in..and doesn't obstruct the ceiling mounted projector...the only limitation is your imaginatíon.
But as to a 'left and right' I never tried that with a true double gun (with two triggers) so you'd need to ask H &H. I shot doubles, two shots, yes but with their plastic gun.