Hello Khan,
In general, you can get all the configuration & command references from the following URL, for ASA:
http://www.cisco.com/univercd/cc/td/doc/product/multisec/asa_sw/v_7_2/conf_gd/index.htm
http://www.cisco.com/univercd/cc/td/doc/product/multisec/index.htm
One thing I would suggest is that you should have a well documented network architecture and have a considerable knowledge on the traffic flow through the different interfaces of the firewall, for you to quickly configure the new ASA unit.. You can anyway refer to the existing PIX firewall configs and build up the statics, NAT , ACL's etc...
Unfortunately there are no tools to convert the pix config to ASA. One thing you can do anyway is to upgrade the existing pix to 7.0, and when you upgrade the configs are automatically changed to the new format. take that config and put it on ASA.. but this takes a lot of time. You can as well write off the config yourself with the new ASA....
Hope this helps.. all the best.. rate replies if found useful..
Raj