Use bare essentials as much as possible. Make use of light and loose furniture . Do not venture out modifications of electrical network and plumbing pipes unless if it's a must. Frankly it should be lived-in house so you don't have to decorate it with many added impediments.
Colours are always very personal, therefore can not be generalised. However, white furniture can go very well with any pastel shade or simply white painted walls!
I admire your society has a strict no grill policy. For any full height window you essentially need protection for children, which can be achieved by simple railings up to about 36" to 42", made out of steel/ wood/aluminim/ glass depending upon overall decor and budget. A gap between railing and window of about 6" will also help in creating space for curtains and discourages children to lean over.