You are indeed fortunate to be able to find such aerial roots from figs that will produce shoots. I have tried to grow many Australian fig species from root cuttings without success, and as far as I know it is not possible with the Australian species. I did stumble on the fact that some exotic species of fig would produce shoots from root material, when a Natal Fig (Ficus natalensis) sent roots into the ground, which were cut off, left in the ground and they shot into branches and leaves. I suspect that it is Ficus natalensis that you are using to get these propagations. I have managed to graft shoots onto aerial roots but the roots must be vigorous and have a thickish cambium layer to be successful.
In answer to you two questions
1 cut the oblique ends back to just above the new shoots and they will blend and taper with time and more growth.
2 Looks like you have already wrapped them.It will help them to fuse together and produce more aerial roots.
Nice going, you are doing just the sort of thing that I love doing.
