Bill
The delta ring is that spring loaded doohickey at the rear of the forearm, between it and the frame. It can be a two person operation as it is hard to pull back all the way and hold while changing out the forearm. Look at your new quad forearm - if it has "lips" at the front and rear, then it is designed to mount using the delta ring method. These lips fit under a piece near the front sight, and under the delta ring, holding the forearm in place. The screws you mention are probably to add stability to the set up. Most AR parts makers offer a tool for compressing the delta ring to make installation easier.
On a free floated forearm, usually the delta ring is replaced with a fitting that allows the new forend to be screwed on, eliminating any tension on the barrel. This method is said to produce slightly better accuracy, but my most accurate AR is an M-4 with the standard forearm attachment method.
Larry