10s - I think it’s a silly mistake. If you use the map command rather than transit into that map. The tank is already spawned.
42s - From the inception of Steam in 2004 to an update in 2013. This freeze bug was present after each and every loading of the game. It was a very big issue among the few souls who ran the game. Until the year of 2011 when rofi found the solution to all of our problems. It was the mighty fix of all fixes… clockwindow 0. And that my children is the story about the freeze glitch.
69s - Using the trigger should be fairly easy. Getting over the fence I’m guessing is harder. But maybe use after the first fence.
For HL21 tricks I’m not sure, it’s all about personal preferences. I’ve seen plenty of HL21 stuff adopted or modified for SS/RTA that I never thought would be plausible. I think you gotta try out each trick and determine it yourself. As for stuff found but not used, nothing I can think of straight out my head. Could look deeper a bit later.