Hey guess never done it before but if I sign up for the developers version of 8.1 can I remove it whenever I want? Or am I stuck with it? If att doesn't release the official WP 8.1 till summer may as well try developer version in the meantime, as long as I can still get the Nokia updates and can remove the developer version whenever I want. If not I may just suck it up and wait! I am not worried about bricking the phone...dont think this is like android, but I want the option of going back to att settings. Sorry if this has been addressed!!
You can't remove it. Once you get the update, you can't go back. You can still choose not to install the update and opt out of the developer preview.
You will get Lumia Cyan when released. The update on the Lumia consists of: 1. M$ portion (which is 8.1) and 2. Nokias additions (Cyan). with the official update you get both in the same pack. If you install 8.1 trough developer preview now, you'll only get Cyan as an addition to it. You won't brick your phone (probably - keep the battery full trough the update and plug the charger in just in case).
I don't know what att settings you're talking about, but your APN and MMS and all that jazz will continue to work. Only issue may be that all the apps (even some Nokia apps) may not cooperate with the new update, but the point of the developer preview is for developers to address such issue before released to general public.
Update is fully functional and complete, but all apps may not be. I remember there was some issue with one of Nokias apps with GDR3 preview, and it got fixed before the Black release.
This is not some nightly beta alpha build like you're used to from android world, this is like pure android found on Nexus devices when it's released to manufacturers so they can install ugly themes over it and ruin the design. Except that android only pushes proper android on Nexus devices, M$ does so for all devices, because the core OS in untouched my manufacturers.
Someone correct me if I'm wrong, but I think I got the most of it.