The first one happens ALOT to me too. When I (1) first run Blockland (2)start/join a server (3)try to edit my avatar.
(1) My avatar will look like shown picture (all black). When I go to the avatar settings it will be all blank (like NO colors chosen and no decals or icons shown on anything. (2)same as 1. (3)same as 1, but it takes more to explain. Sometimes when I edit my avatar, once I click send everything will go blank like 1. I need to go back to the avatar editor and click send a few times for it to go back to normal. I asked Badspot about this glitch but he said "This does not occur in the default game."