Nollies up, over and down things are one of the best feelings ever, they're easier to learn up stuff coming at an angle at first, start even almost parallel if you need. That will kind of force you to (naturally) shifty your way up there but at least you'll get the right timing down as well as the backwards type of momentum on the jump (the key is to push your nose ahead of you by extending your whole leg and not just lean over the front of the board and wait for magic to happen). Then you can work on your angle of approach by gradually coming more and more perpendicular, eventually you'll get rid of the shifty technique or even learn how to control it (honestly, big shifty nollies are so fun). Also the number one thing to keep in mind with that trick over an obstacle of any sort is to pop early, like a full deck length earlier than you would pop something ollie-based over the same obstacle (so speed helps). Just pretend that if you don't, then you will clip the obstacle because well, that's exactly that will happen (or down stuff you will have a harder time getting proper pop). Also binge watch Paulo Diaz and realize it's one of the best tricks.
Sw pop shove I find super easy to control by popping off the big toe at the tip in the very middle of the tail (which I normally don't do for switch scooped tricks) and then you have to kind of nudge the board forwards so that you stay leaning backwards and don't naturally jump ahead of the trick, if you keep your shoulders in the same axis the whole time it should just start working. It kind of feels like the placement/pop/scoop type of a switch backside 180 if anything and then you can try getting the kind that's caught so early it feels like it never left your feet.
For ollie impossibles, no matter the board size/shape mine is always the same (in fact I find that trick to be one of the least set-up-dependent tricks as far as I'm concerned), back foot is always located across the whole width of the board and nested just behind the back bolts (I can actually feel the concave under my sole prior to popping and that's how I know I'm going to get the wrap).