As the appearance of the garden has a modernist style with the straight lines and concrete furniture how about a Mondrian influence and add a bold strip of blue? It is a pond and with the right shade it could look really relaxed and contemporary. My daughter's suggestion is a chalky lilac!

Deep gray and all the other accents in silvery old wood and cream. This will add drama, allow the other elements to bring ion light and set off the concrete wall as a true feature. If you want light instead of drama, then go for a very pale beige stone. It will echo stone colours in both the concrete and rocks...

I would love the rocking chair too, but way too expensive for me, unfortunately!! Yellow could be good... hmmm, will have a look, thanks

For a pass through window to be very useful, it needs a surface to place items that are being passed through, that can be easily reached from both sides, or you would need to coordinate people inside and out to pass things, which isn't feasible. I would consider whether it will be used as a pass through, given the door is immediately beside it. A small breakfast bar that uses the window for a view can also be useful for a pass-through set-down surface. Make sure the window is large enough to give a line of sight from person to person so that it is easy to communicate between the spaces - along the lines of 'Could you grab another beer?' or, 'I forgot the sauce.' I would also make the pass-through window a little wider if you do have a seating area, so it looks big enough to be welcoming, or it will be less likely to be used. At 2.500 deep, the deck is not large enough for a comfortable outdoor dining area of more than a couple of people. You need 600mm for comfortable seating on each side of a table, plus the table width which will be 900-1200, and with this layout, you also need another 900 mm to allow access past this, to the pass through, the seating and to the steps down, and with the deck being above ground level, space for access beyond the seating on both sides of the table is a good idea. If there is a barrier, you can get away without it because chairs won't fall off the edge, but it does make things tight. That adds up to at least 3000-3500 and preferably more. You can make things work with a tighter space, with a compromise to fixed seating along the edge, and a narrow table.