I have trained with many Wing Chun students and they do quite well in Systema; I would say it's one of the Eastern styles that blends very well with Systema principles.
Although we don't call it the "one-inch punch," the phrase is often used in class when this is demonstrated, just because many people are familiar with it. Simply stand close to your partner with your correctly-formed fist touching his stomach and your elbow bent at right angle. Of course you can use this on any area but I recommend the stomach as it's dense enough to make it challenging if your movement is insufficient. Then rotate your shoulder to generate the punch. Do not draw back or "cock" your fist; generate the strike with your fist already touching your partner's stomach using the rotation of your shoulder to initiate the movement. When done effectively your partner will verify it; he'll be able to feel it and may need to take a step backwards or otherwise yield from it.
When you have mastered that, you can try it from "one inch" away if you like; there's not much of a difference. Then, when that's going well, try to do it with as little shoulder movement as possible, that is, "invisible." If someone were looking at just your head and shoulders, they wouldn't even realize you are punching at all, because of the "invisible" internal movement. This is difficult, to be sure, but there is much advantage in making your movements small internal ones rather than large visible ones. You can also practice generating strikes from other areas of your body with internal movement, but for the so-called "one-inch punch" the shoulder rotation is the easiest place to start.
As far as the "chain punches" not really sure what those are in Wing Chun, but Systema has "three dimensional strikes" or the "trinity strike." I don't agree that straight line is always the shortest route to the target; if a straight line causes your strike to be instantly discernible by your opponent who can then easily avoid it, it wasn't the shortest route, or any route at all. However it's as good a place to start practicing as any.
I also don't agree that you don't get a chance to string together a chain of anything in Systema. Continous, dynamic, fluid movement is a hallmark of Systema, and in general, every punch, kick, and other movement should blend into the next one until the conflict is resolved. The tricky part is that you can't plan ahead because you don't know exactly how your opponent is going to respond. There's no point memorizing a series of steps, because the way people move in physical conflict is somewhat unpredictable. Pain compliance is a bit more predictable; with a hard joint lock or finger-jab into a sensitive place like the groin, many people will respond in similar ways. But with evading strikes and kicks, there's no way to predict which way they will move, so your brain and body must remain ever-flexible and adaptable. No time to plan for the next move; just move.
To get started with multi-dimensional strikes and kicks, practice getting at least three strikes or kicks from a single movement. You could strike with the fist, then the elbow, then the fist again, without retracting your arm. Go slow so you can see the effects of the first strike. Perhaps the person will double over, making it convenient to strike the spine with the elbow. Likewise with three-dimensional kicks: strike with the foot, then the knee, then the foot again, all in a single "step." Get used to the biomechanics of this before attempting it as an offensive move. Ask your partner to simply yield in the direction of the strike or kick so you can see how it works. Only when you feel confident in the biomechanics of it should you spar with this multidimensional approach.
The multidimensional kicks do require good balance, so if you cannot stand on one leg without wobbling around or flailing your arms, practice standing on one leg, then the other. Have your partner push you gently while on one leg to further improve your balance. He should push you just hard enough to challenge you, but not knock you over repeatedly. The goal of this exercise is not to prove how easy it is to knock over a guy standing on one leg but rather to help you improve your balance. Good balance is important for true dynamic Systema motion. It's harder to take someone down if they have excellent balance. The irony is that good balance is almost impossible to achieve without relaxation. When practicing balance exercises, let your mind be free of the pressure of the goal of staying on one leg. You cannot force yourself to be relaxed no matter how hard you try, and you cannot force yourself to have good balance. You just have to relax and let it happen.
I hope this helps. For background reference, I have been training regularly in Systema since 2003. I am not an expert but I've had the privilege of training with many senior Systema instructors and have learned much from their classes and seminars. But no matter how much I learn, there is always more to learn, that's the exciting part of being a Systema student.