Would the IMEI of all my apple products be in my Apple Account, history if ever. I lost my Iphone 5 and need to block it

IMEI numbers only applies to cellular devices, so if you have iPods or wifi-only iPads it won't apply to them. To get the IMEI number for your phone (you've contacted the carrier ?) : Find the serial number or IMEI on your iPhone, iPad or iPod touch - Apple Support

You can't block an phone yourself with only the IMEI number - it would have to had Find My iPhone enabled on it: some carriers can brick a phone from the IMEI number so you may or may not be able to get yours to do that. In the meantime change your iCloud password. Sign out of iCloud and iTunes on all your devices before doing this.

If you go to appleid.apple.com you can see a list of all devices you are signed in on with your Apple ID. Clicking on any phone listed will show it's IMEI. If you want to block your iPhone from being accessed if lost go to iCloud.com. From there sign in, click Find iPhone. From there you can see the devices location if it is on and connected to a network. If it's not it will show it's last location. You can also play a sound from that page to ping it. As well as click enter lost mode which will lock the device and allow you to input a message and a phone number to call for whoever finds the iPhone to be able to return it to you.