I believe the lag and clunky downshifts into 2nd are separate issues.
I posted about this in another thread and it seems like a fairly common issue. I have DCT software dating to 2010 and others had the latest versions. I find that you learn to drive around it via the way you brake and/or the car learning your driving habits. Use to be surprised every now and then by a thud when the car downshifted into 2nd on its own, but can't remember the last time that happened.
I don't think it should occur every time though and shouldn't happen if you're downshifting on your own. The car not being smooth from neutral into gear would also concern me. It's a "lifetime" fluid and all, but I'd get the fluid checked if the problem persists. I'd also try driving another DCT car to see if it acts similar.