API: Add more details about items

It would be great if the API was able to fetch and update all the information about items.
Right now details like time-tracking records (individual entries, preferred, or, at very least, the total) and, also important, custom fields (used to categorise stuff by different criteria) are missing.
Surely there are other pieces of information missing. But those 2 are the ones I've detected as "needed" (for me and my integration plans).
Ciao :-)