Looks like aluminium angle thats been cut with mitred corners, Thats if I'm looking at the same thing as what you're asking.

Hi, Just remember the Light Reflective Value (LRV) of a dark colour particularly in Queensland's Summer may cause warping of the lining boards, before painting them strip off the old paint - likely to have been lead based at some stage could be 3 layers deep (easily tested by a test kit from a paint shop) and seal all the holes and gaps with an oil based sealer, then apply the 'filler' - builder's bog etc and paint over, with a good quality acrylic paint - Solagard type exterior paint system. If you don't seal the boards before applying the filler; moisture - condensation will migrate from the back of the board to the face - no sarking to the back of an older weatherboard homes and cause the filler to go 'soft' and blister the face of the board ruining the paint, (4 years as a Trade Paint Rep). As far as asbestos cement sheeting - protocols are in place for its safe removal as any home built prior to 1983 is 'likely' to have asbestos lining materials in the wet areas, laundry, flue pipes, kitchen lino or underlay and probably the meterbox - all the usual suspects. These homes look fantastic when restored properly and I've seen quite a few done 'upside down' with the sleeping areas on the ground floor and entertaining / living rooms on the first floor, that way the rooms below can have all the modern fixtures, finishes and insulation without detracting from the liveability of the upstairs rooms not needing the same level of noise control, or hiding electrical or plumbing lines etc in wall spaces.

White and cream can work together and it is a great idea to paint all your trim white to freshen and lighten your room. Whether your cream blinds look dirty if you paint the trim white will really depend on the cream tone/shade of your blinds and possibly the material they are made from. Remember the colours will look different of an evening under artificial lights than they do during the day under natural light. We have uPVC white window frames with classic cream architraves. I recently purchased some block out roller blinds and spent hours agonising over whether to match the windows or the trim so I understand your dilemma. I ended up matching the white of the windows because we wanted the blinds to 'disappear' when they are opened. Have attached a pic to show the white windows with classic cream trim fyi....

A photo of your house might help Houzzers advise better! Feel free to share