1 - no to demolition, station is already largely of a suitable standard. A nice low priority upgrade would be replacing the current subway and ramps with one that is wider and more open with a direct connection through to the Bakewell Underpass shared path, but otherwise retaining the present platforms.
2 - no, Adelaide Showground is a massive improvement on the old Keswick station and should have been done much earlier.
3 - no, too much expenditure (including additional platform at Adelaide Showgrounds) for too little gain.
3a - no, it’s an important local link which must be retained.
4 - why?
4a - the local hydrology would dictate an overpass, not an underpass. I'd go with rail over road, and ensure that it is built with passive provision for future widening of Cross Road to provide the link between North-South Motorway and the South Eastern Freeway.
5 - it's not harming anyone there, let those who want to get rid of it pay to do so.
6, 9 - no. Perform minor maintenance as needed, otherwise they are already of a suitable standard (platforms and shelters are provided) for their patronage.
7 - no problem with this one, but I struggle to see the benefit it would provide.
8 - no. It’s handy for providing a place where a broken down railcar or track machine can be stashed.
10 - no to demolition, station is already largely of a suitable standard. One minor refurbishment couldn't go astray - replacing the wooden planks on the ramp with the same modern non-slip plastic/aluminium planks used on modern footbridges.
11 - I agree with kipioneer, what land?
12 - no. There are many other crossings which would be far higher priorities for an upgrade. As a practical matter, an overpass would be better suited to the location than a subway.
13 - not strictly a Belair line matter, but if ARTC see the benefit in doing so then they can go ahead and do it.
My top short-term priorities would be:
1 - resignalling to allow simultaneous entry to passing loops, and automation to deal with the "congestion" (controllers queuing up at the coffee machine) that affects trains arriving at Adelaide.
2 - reactivate the shelved project to replace the Goodwood subway with a new overpass incorporating both station access and the Mike Turtur Bikeway.
Apart from that, any other capital expenditure on the Belair line should wait until its future is resolved.
1. electrify and resignal
2. reconfigure passing loops as needed to support operation by S-Bahn style EMUs optimised for rapid acceleration.
3. Bellevue Heights station
4. Upgrade of Mitcham pedestrian subway to also pass under ARTC line and meet modern standards for ramps.