I have recently been a TA and I realised I have a large collection of comprehensive notes from my alma mater dating back to my Bachelor degree courses. I wonder if this is an acceptable practice to share them without my professor's consent (since this is purely for education purpose)? My student is asking for these notes, and I told them I should ask my professor first.
If these were my notes, and you asked if you could share them with your students you would get permission in a heartbeat. In fact, if I had continued teaching the course, and thus continued to develop them, I would probably sent you the most up to date version of those notes. I am not alone in that, I remember that several associations have been trying to set up a repository of such teaching notes, which struck me as a good idea, but I don't know what came of that. However, I have come across people who take a more restrictive view on their notes.
So, I think the best thing you can do is ask. Best case is you get the most up to date notes and a potential reference writer gets reminded of you in a positive way. Worst case (s)he says "thank you for asking, but I don't want you to release those notes". If you don't ask, release the notes, and (s)he finds out, things could get a lot more ugly.
I would share my own course notes from when I was a student. It is common to exchange them with other students while you're still a student, why shouldn't you share them when you have graduated?
Often student bodies collect notes from previous years and allow students to copy them. Give them the notes and be happy that other students can learn from your notes.
You may or may not have a different stance on solutions for exercises, as they are often (almost) the same in the same course. This is up to you, but in the end everyone is an adult and needs to learn responsibly himself.