Hi,
I've personally come to this doubts myself, when I was beginning to develop
for Replicant.
Paul K. has written an interesting post on his blog, about the "free-ness" of
google's android SDK:
http://code.paulk.fr/article0008/what-s-up-with-the-android-sdk
I don't really think it solves the question, but it gives many interesting
suggestions, so I suggest you read it.
Then, asking on the Replicant forum for help, I received this reply from
Wolfgang Wiedmeier, about three alternatives, including the SDK in Debian:
http://redmine.replicant.us/boards/21/topics/13931?r=14002#message-14002
In the same thread, I explain the way I got to successfully start developing
with the Replicant SDK, using Eclipse as an IDE.
Please read this page for general instructions:
http://redmine.replicant.us/projects/replicant/wiki/SDK
That page is a little outdated, but I'm going to review it in the next 10
days, to include my experience and the way I got to use the SDK. Anyway, even
now, it should give you enough clues on how to put up a developing
environment.
My suggestion is to avoid using Android Studio, as I strongly suspect it
contains proprietary code.
Using Eclipse should do well enough, once you get used to it. The only
feature that's missing is the wysiwyg editor for the layout, but I found out
that it is far from being essential; you will do better with manual XML'ing.
For anything else, feel free to ask in Replicant's froum, and you will get
more direct helping.
Happy hacking!
Fil