I am going to release a Technical Report that will be archived and made available online by the university's library. An abridged version of the work was accepted by a peer-reviewed conference and will be published in the proceedings. For this to happen, I have to sign a copyright form, assigning to the publishing institution all rights under copyright.
a) What is the best way to grant readers of the Technical Report the freedom to quote (unlimited length), distribute, and build upon the work? And point out that they have this freedom without asking for my permission?
b) Is a Creative-Commons License the way to go? If yes, in what form should include the lincense in the work?
c) Is there any conflict between the copyright form for the conference paper and releasing the Technical Report under an open license?
Similarly, I'd also recommend the Creative Commons Attribution Licence (CC BY). A good guide explaining why this is best, written by the Open Access Scholarly Publishers Association (OASPA) exists here. This would fulfil all the criteria you ask for in a)
However, it does matter how you convey this licence. For example if you included just a CC BY 'badge' as an image in the PDF, it would be difficult for a web crawler or machine to detect that the manuscript is Open Access. Thus it's good to signpost the licence in a clear machine readable way
This work is licensed under a Creative Commons Attribution 3.0 Unported License.
(specifically including a URL link to full terms of the licence, and make sure you choose the unported license, rather than any of the country-specific variants)
With respect to c) the trick is (if it's not too late now) to upload your CC BY version as a preprint before you submit to the journal & their draconian terms & conditions. Journals can't stop you uploading your work before you've signed any agreements with them. Some journals don't 'like' this and will reject submissions that they know are openly available on the web prior to submission, but these journals represent a small-minded, old-fashioned minority in my experience. Even Elsevier allow preprints!