In django, is there a way to directly annotate a query with a related object in single query?

Yes, it's possible.

To get a queryset containing all Chapters which are the last in their Novels, simply do:

from django.db.models.expressions import F
from django.db.models.aggregates import Max

Chapters.objects.annotate(last_chapter_pk=Max('novel__chapter__pk')
    ).filter(pk=F('last_chapter_pk'))

Tested on Django 1.7.

No, it's not possible to combine them into a single query.

You can read the following blog post to find two workarounds.