The tightness comes from the fact that the balls inside the inserts have to break in is my guess. I think that once it is run a couple of times it will free up nicely. Right now, the balls are a bit tight on the inserts.
Yes, it seems the slop comes from the hinge pin on the arm hole. They might be a little off spec. However it's not that bad.
Yes, tapping the holes into the plastic ball cups and plastic parts would definitely be helpful and recommended.
I used the kit bladders, however ours will work with the shocks.
Much like with the T4, the people that are neurotic about breaking it, would break any type of front bumper. In order to break a front bumper the collision would have to be very direct and very hard. My 417 has a bumper like this one and I have never really had trouble. However, is it weaker than a TC6 style bumper, sure! I don't think it's a deal breaker though.
The battery can be moved in and out, but not back and forth. We have been working on a new universal battery stop system that would work on this car, and most cars with tape slots, which also allows the battery to be moved fore and aft.