Dmitry Selemir
Hi Mervyn, apologies for late reply, am away at the moment with limited internet access, hence no PoD the last few days. Going back to civilization soon, so will be back in action properly.
Regarding following. We are thinking about ways of changing the whole following process as it is not working very well right now. You do have to click follow' to start following a new person. This manifests itself in ability to filter out publications by people you are not following and also the red indicator on your left shows you how many unread publications by the people you are currently following there are. The people you start following do not get notified about the fact you started following them — we wanted to make sure the following is always meaningful and not done in expectation of reciprocation.
Going forward we are thinking of getting rid of filtration and instead start personalising the publications you see when you log in, with people you are following being an important factor for that. 
Sharing publications from your Twitter account is fairly straightforward.
You can either:
Click on twitter button on the righthand side of the detailed view of publication you want to share, edit the suggested text, adding the hashtags/descriptions etc. 
You can copy the link from the address line and just paste that link into the create new tweet window directly on Twitter. Don't forget to add the title, name of the author.

If you are not uploading an accompanying image — we have Twitter card installed, which means that if there is an image in the publication — it will get used as illustration and also short description will be displayed under it. If there is no image — the system will go with author's profile picture.

Hope this helps!