Field Visibility and Display Modes:
Since version 6.x-1.1 , the module does not hide the field in the node's content area anymore. You can do that for yourself in the display settings for your content type.
CCK blocks will define a display mode named "CCK Blocks", which you can use to configure the display of fields when they are appearing as blocks.
This allows you show the field both in the node's content area and in the CCK block, with different display settings.
IMPORTANT: Before any of your CCK blocks will show up, you need to set the field in question to be visible in the CCK blocks display mode! See "step by step", below.
Performance and Caching:
Since many users have experienced tremendous problems when block caching is activated (#400858: CCK Blocks appears to be incompatible with block caching), we decided to disable block caching for cck blocks.
If you wish to have block caching, please use the Block Cache Alter module to activate block caching for individual cck blocks.
Block titles support tokens from the token module. You can make use of this to have a field as block, with another field value as the block title.
To do this you must download the contrib Token module for Drupal 7. The token module that comes in core will not provide the field tokens that you need.