Yes, all copyright permissions (letters, e-mails, forms etc) must be retained by you for as long as the copied item exists.
No! No response does not automatically give you the right to use an item. Try sending a follow-up email, make a telephone call (if possible), and if everything fails try to find an alternative. If do need to include it in a thesis you should make a note to omit this image from copies made available to the public.
Legislation allows for the provision of accessible formats of copyright works for people with any sort of disability. This includes, but is not limited to, large-print, braille, captioned, or audio versions of a work.
Image: Basilio Briceño, CC-BY-2.0 Generic
This 1906 advert contains some good advice but remember: Copyright is automatic.
You don’t have to register or pay for copyright of your work.
Image: Columbia Copyright Office, advertisement from the New York Clipper, 1906 (from Wikimedia Commons, in the Public Domain)
Under the 1988 Copyright, Designs and Patents Act, ‘fair dealing’ allows the limited copying of copyright material for research and private study. You’ll be pleased to hear that copying technology has moved on!
Image: Stewart, Francis, War Relocation Authority photographer, Topaz, Utah. Rose Nakagawa, former student from San Francisco, California, now works as a mimeograph operator..., 1943, from Wikimedia Commons Public Domain
Copyright protects your work from being used without your permission and allows you to profit from it. And it means you don’t have to lock your books away in a cage!
Image: Winifred Lao, Protected Books, Morgan Library, CC BY-SA 4.0