Welcome! This December will be two years of wet shaving for me (wow, time flies), but I'll try to answer a few of your questions based on my own experience. For most things wet shaving, the "your mileage may vary" adage holds true - what works for me may not work for you, and vice versa.
I have been looking through videos and things to get a better shave around my chin and jaw line. I definitely will be practicing, but i was wondering if it may just be these van der hagen blades. I bought an amazon variety pack of blades to find which one i like best, but i am nervouse about using the super sharp ones until i can stop knicking myself already.
I can't speak specifically about chin and jaw line because I shave my neck, cheeks, and below my lower lip, leaving the rest of my facial hair intact and trimming it with a beard trimmer + 2mm guard. With that being said, I had slight challenges in those areas in the 4 or 5 times I've gone fully clean shaven with a safety razor. What I've learned is that continuing to hone your technique develops a muscle memory of sorts, and all of a sudden you're navigating your face with full knowledge of the grain, how much pressure you need to use, where you need to buff or make shorter strokes, etc. Give it time.
I do recommend the TryABlade sampler pack vs. the VDH blades, as others have recommended. Technique will be far, far more important than blades. In my experience, I was terrified of certain blades that carried a reputation (7 O'clock SharpEdge, Feathers, etc.) and when I finally bucked up the courage to try them, I thought "what's the big deal?". If you have bad technique, you'll hack yourself up regardless of razor + blade pairing. If you have good technique, you can get a passable shave with just about anything, even if you notice a bit more bite or sharpness from one blade vs. another.
Is there a step in prep that helps the shave get closer? Not sold on shave oil yet.
Good lather + technique. I went through every pre-shave routine in the book. None of them ever really harmed my shaves, but it was spending needless money and time on something that did nothing to enhance my shaves. A good, warm shower will soften the whiskers. A nice, slick lather will allow you to glide over your skin without irritation. Good technique with a capable razor and fresh enough blade will reduce the beard, and you'll be set.