Disposing of 2010 27” iMac securely

I will be removing my self-installed SSD hard drive from the 27 inch iMac and using it inside an external case to be attached to my new MacBook Pro. I may also remove the iMac’s RAM chips.

The above brings up a couple of questions

1. Will the remaining shell of the iMac - without Hard drive or RAM - have any possibility of still containing personal data inside it?

2. If I forget to first de-authorize that hard drive from iTunes would I be able to do it after the fact from its external case?

3. If I do first de-authorize it from iTunes is there anything else I should de-authorize such as iCloud or other?

4. My intention is for it to remain in its original state and from its new external case be able to boot from it if necessary to conduct any maintenance on the MacBook Pro

5. Last question how do I dispose of the remaining hardware? Is it then like any other recyclable trash?

hope the above makes sense and thank you very much in advance for any suggestions anyone may have