Few things that you need to consider.
1. Is the laundry area located on the ground floor (landed property) or in a condo (above ground floor)?
If yours is on the ground floor, they can easily install from the outside. Else they will have to take out the grill to be able to install the window if your place is not on ground floor.
2. Is the plastering around the grille opening perfectly square? Cos the window will be square and if the present opening is not, then there will be gaps at some of the edges.
3. Normally the windows frame will be installed with some portion embedded in the plastering. Avoid water seepage and also there will not be any gaps between the frame and plaster.

As for your concern about the alarm wiring. Mostly the alarm wiring are running on the inside and connected to the grille. You will be installing the window on the outside. So, the chances of damaging the wiring is very slim.