Generally, horizontal grilles are easier to climb (like a ladder).
In this case, the gaps of the gate are so narrow that you can't put your toes through.
The smaller grilles above the walls would be climbable.

OK, maybe the gate doesn't make much difference, with robbers getting so daring these days.

It does apply to handrailings for staircase and balcony. It is safer to have vertical grilles which is climb-proof rather than horizontal grilles, if you have toddlers around the house.

You'll have to get a quote from a cleaner. No two houses are the same la.
Cement stains is easily removed with acid (sulphuric acid), available from hardware shop.

Mounting which you can adjust the angle of rotation, as in computer monitor. The one you show is fixed, not tiltable.