I think I found the issue with #1 - the system would not work properly if the list of record id's was delimited with colons, but worked properly when those delimiters were changed to commas. Again, it worked in 4, but not 18. I am still trying to figure out the answer to #2...
Regarding #2 it's not clear what you're doing. What do you mean by 'enter a key' ? How is the page constructed on which you're expecting date fields to be pre-filled in? Are they database columns or do they have some other process to populate them? Have you upgraded any parts of the application to change behaviour of any items/pages?
We've just upgraded from 5.x -> 18.2 and date pickers appear to work the same way as they did before. Typically they're populated by automatic row fetch in most of our forms. I've refreshed some themes but not performed any application upgrades.
I am pulling a record where the textbox with auto-fill is the primary key. The auto-fill field works fine. The two dates are fields in that table that I am trying to populate into the Apex form for possible editing. These are what are coming up blank, even though I know that they have values. This functionality works correctly in v. 4, but does not appear to be firing the dynamic actions after updating the auto-filled text field in 18.