Will I be able to download websphere on linux for free for development, learning and non-commercial purposes (like weblogic)? Functionally, are websphere and websphere CE very different? Where can I get such docs?
IBM offers trials and betas on their website, but I've yet to hear of a free non-commercial version (although there might be one). I think the current trial allows use for 60 days.
Although (asks google) there does seem to be an academic program at http://www.alphaworks.ibm.com/academic although it may be you need to a professor or university admin to participate. You could try e-mailing someone at ibm for more information.
Websphere CE is free. You may also get 3 month test versions for Websphere AS or Rational Developer (the IDE). For more general learning purposes I would prefer Websphere CE. Its based on Geronimo, not on Websphere "classic". Both are completly different technology stacks. From a functional pov both are j2ee application servers. I haven't worked with Websphere CE. Anyway this looks like a promising starting point: http://www-128.ibm.com/developerworks/kickstart/
Actually I take that back, if you create an account and sign up for the Academic Initiative (takes time to process and you must be verified as an active student) then yes, IBM allows free use of DB2, RAD, and WebSpehre.