The Kindle doesn't run Android, so you can stop that line of thought right now.
AFAIK you still get 50 MB monthly on those old devices.
My only experience with the browser TBH is the skipstone browser available as a jailbroken addon for touchscreen Kindles only. You will have to explore which websites work yourself.
(Javascript-heavy sites will often crash the browser though -- probably because of the lack of RAM.
)
...
I think someone (twobob?) tried to get a VOIP client running on the Kindle, can't remember if anything ever came of it.