Depends on what you want them to look like at maturity. If you want them to retain full crowns down to ground level, then very wide spacing, about 10-15m apart. If you don't mind the lower branches dying off like trees in a plantation, then they can be much closer together.

Ditto for the wall; if you want the crown retained, then at least 5-7m away; if you don't mind the branches facing the wall (and below the level of the top of the wall) dying off, then it can be as close as a metre. Any closer than that would not be advisable as the trunk may cause structural damage to the wall.

Resin

You don't say what the purpose of the planting is. Is it for a screen to block the view of something, or the view of others into your yard?

For a screen planting where these trees grow well (I assume you are in an area where they are native or well adapted), then about 15 feet apart (4 to 5m) would be a good spacing for when the trees grow up, but they could be spaced further for more full crown development. I assume they would have full sun on the side facing away from the wall so the lower branches will be retained. If you want faster screening, you can plant them closer, but when they mature they will be too close. You could plant them close and then thin every other one later to get a 15 foot or so spacing.

I agree with Resin's information also.

--Spruce