Go on the Delcath FB page or the Delcath Discord Chatroom these have been answered and by me as well in September. But here goes
1 - The D is all about how ticker changes during a RS or when a stock issues new stock- it becomes a new ticker during the RS time period and gets the D. The D indicates this RS and the creation of new post RS shares to be traded. In other words and for Delcath's sake there is a RS and Dilution happening simultaneously.
2. The voluntary delisting preventing non Hudson Bay and Jenny controlled proxies from shorting the price beyond their strategy. Also this further made it more difficult for prior SH to go after them during their blackout period.
I would not be surprised to see another RS in 2018 pre summer. But you will definitely see dilution and heavy convertibles (and then a RS depending on float and their shorting).