
For installing Mods you could use this DAO Modmanager. ( When it is a mod with a dazip or override extension. )
As for friendly fire ... well be prepared for that because that is a very real possibility. You could use No Friendly Fire Damage and play on easy until you know the game better. But other wise you will need to get used to getting and giving Friendly damage. I have that mod installed as well and on easy it definitely worked, but as intended after switching to hard difficulty the chance for Friendly damage was back. But till now only Wynne seems seems to be the only one who has caused Friendly Damage with the Earth Quake spell. ( So I removed the tactic rule that made her use it. )
As for the rings ... well yeah I can understand why people like to get rid of them at times, but there are also times where I personally think it is good to have them. For example ... in a certain town you are asked to help defend it against a night attack on the town. During that attack it is really useful to at least see who is the enemy and who fights on your side. Enemies have red circles around them while your team members will have yellow rings ... and those who fight on your teams side but are not a member of your team will have blue rings. ( But once you get used to EMAT you will not have to care as much, since with the right tactics and behaviour, you team will mostly be fighting in real time. )
But I installed the No rings mod just now and will see for myself this evening whether it is still good enough or not to keep installed. ( Due to what I wrote above. But Screenshot moments come to mind.

And it does seem to work from a quick check. So to keep things easy to install and remove ( If you download the manual version. ) go to C:\Users\Whatever you have here\Documents\BioWare\Dragon Age\packages\core\override\ and make a folder. ( I just named it circle. ) After that just dump the VFX files from the No Rings Mod in that folder. ( No need to tell you how to remove the folder you made.
