A few thoughts
As already mentioned you're definitely back on the ski and working with a straight front leg a lot. That's ok and pretty common; just keep working on moving your weight forward on the ski and getting comfortable/confident. You'll feel like you have almost all your weight on your front foot and that's ok. Everything feels exaggerated back there so what feels like almost all your weight is probably about right.
In terms of the straight front leg, try this. Stand up in your slalom stance, weight mostly on your back foot, and a straight front leg. Now think about bending your front knee. You have a bent knee now but do you still feel like most of your weight is on the back foot? Now get back in the original stance, and instead of thinking about bending your front knee, think about bending your front ankle. Your knee automatically bends and your weight has to shift more forward.
In order to 'glide' properly you want to be free of the boat and that means going about the same speed or even slightly faster. You don't want a lot of slack on the line, but you want to be free from the pull of the boat. (mentioning b/c you commented like you felt you were ahead of the boat, which isn't necessarily bad, but can be some times
) But notice on some of your pullouts, as soon as you stood up out of your lean you started getting pulled back in by the boat.
Ski porpoising - I'm not really an expert here but I'd guess it's at least somewhat related being so heavy on the back foot combined with the slower speed so it's sinking a bit. Maybe related to the size too? While you're at Coble's don't be afraid to ask about your ski, they can get it set up or provide recommendations if you want to try something else. You're right to question it though that's an indication that something is off.
Wake crossings - As mentioned this is something to build up over time. Start just barely outside the wake so you don't feel as fast. Over time build up a little wider & wider, eventually you want to do it from as wide as you are on pullouts (or wider). It sounds weird now but eventually crossing the wake faster in the strong position will feel a lot easier than trying to plow through it.
Your comment said 65' rope, is that a wakeboard(spectra) rope? Normally a slalom rope would be 75' (long line), or 60' (15 off). If you're using a spectra line you might think about getting a slalom rope/handle since you actually do want a little bit of stretch there. If you do get one, ski at the 60'/15 off (red) section.
You're looking pretty good so just keep at it and don't get discouraged. Improvements take a lot of time so just enjoy the journey
Get some gloves!