A block is simply a share that has a high enough difficulty. Right now, the network difficulty is exactly 12,153,412. This means that if you get a share that's diff=12,153,411, it's just a share. If you get a share that's diff=12,153,413, it's a block solver.

Due to big request we are going to give the possibility during the next batch pre-orders to buy units with 2,3 or 4 modules, along with the possibility to separately order the modules when you need them. This will also be a great opportunity for avalon batch #1 buyers that have just 3 modules and want to upgrade to 4.

More on this will be published in the next days 

You have to edit or add a .conf file, e.g. under unix:

mkdir -p ~/.nibble/;cat >~/.nibble/nibble.conf <<EOF
server=1
rpcuser=nibblecoin
rpcpassword=YourPassword
rpcallowip=127.0.0.1
rpcport=18341
#addnode=machine...
EOF
chmod 600 ~/.nibble/nibble.conf;

This file is required, to setup a password and an user account. In that case the port is set to 18341.