Yeah, grease the back of the seal to hold the spring in. Guide the axle as best as you can, you can get it almost all the way in before you need to let it ride the seal. It will be ok.
Check your bumpstops. I doubt your birfield just died and blew apart if the tire was free to roll. I am sure it was bound up in the fender in some way.
The thing inside your axle is kind of a guide to get the axle shaft to slide in. It was tacked inside the tube but a lot of guys have seem...