stream update process understanding

[meist...@googlemail.com]

we doing a nice diaspora* group imitation script and have some questions

1. is there a way to make a stream update from serverside directly, some sort of call, or does a user itself have to make a browser-like http request?
1b. how is stream update in general done?

2. are the given message ID on a specific pod are consistent, what happens with realy old messages, what happens when original sender (from another pod delete this very old message).
If a message is deleted, does the old ID being 404 - or is there a reuse of this message id?

thx for hints and answers