1: Is there a discord chat for communicating and joining in the discussion?

We have a channel within the @earthnation discord now. https://discord.gg/fpSnkFM

2: Is there a way to see how many people make part of this

We previously published this every couple of days and now will be publishing this weekly. I'm working on it right now and it will come out in a few hours.

3: Instead of using SteemVoter, do you have the possibility to program your own bot

This is part of our long-term plan.

4: To make this really work it must be possible to receive the income also without doing anything

What you are suggesting would require us to have an outside source of income that would create a STEEM flow that could be directly paid out.
In fact what makes @steembasicincome work is that the income is paid out through upvotes- meaning the income is newly created SP/SBD. That doesn't requires us to have outside cash flows.
When we program our own bot, we will enhance it to deliver to comments along with posts, so that active Steemians that register as inactive because they post infrequently can still receive their upvotes. It will always pay out using upvotes, not STEEM transactions.