As for your questions...
1. It is not quite drop in, but comes with everything you need to install...if you are waiting, call LaRue and have them add it to your order.
2. Just as solid, with the built in adjustable cheek rest.
3. No downside IMHO. If you are planning on running a sling, You will need to attach to the bottom rail, no side QD points. When I ordered it larue sent an attachment for this...I don't know if they still do that.