Why can't you reinstall the disconnected bake light switch. If the new switches are not going on the architrave, then just reinstall the switch. Keeping with the era of the home.

i'm wondering why there isn't already an internal laundry door?.. are the floors and ceilings different heights and is the only entry to the garage through the roller door? biggest challenge will be allowing enough room for comfortable stairs that need a small landing area for safety and a door would help with heat and noise and length of new stairs will depend on floor and ceiling heights but my suggestion includes a fully enclosed stairwell with only an openable window at the end for light and so you can call down from upstairs when dinner's ready...despite your plans' dimensions being a little inconsistent there should be enough space to create a good sized study nook and keep a reasonable living area but you should rearrange the existing furniture (leaving at least 1m by a space up to the opening between living and dining) to make sure you like how it feels ...downstairs using only partitians* and without changing roller doors and/or windows my suggestion include a mum's nook to retain light, a secure workshop area and a minimum single garage...the partitian walls could be built with simple stud framing with walls made out of bookshelves, storage cabinets and some wall lining that need not reach the ceiling to retain some light and ventilation and there are some great garage floor and paving paints that could make a clean floor throughout

How big are the holes? And how prominent are they? For small holes you can stipple the filler with a dry paint brush. What is the original finish? Are they plain textured bricks, rendered, bagged or a texture paint? For bigger patches you’ll need to recreate the original finish.

Professional advice is what is required. The weep holes are intentional and created to help protect the building against damage caused from the build up of moisture inside the wall cavity. So you will have to be very careful with your neighbours wall. Something along the lines of this diagram may be worth looking into. Have a concrete swale or plastic swale to collect water before it enters the hole, then catch that water and redirect into your soak wells. A licensed plumber is definitely required for professional guidance.