How tight should the spreader bases be attached to the mast.
Also how tight should the mast be tightened to the step?
I hadn't thought about thr spreader sockets. They are under compression so probably just snug will do, the bolt is more a retainer.
As for the mast step, it is similar, it carries almost no load under way. Miine has a fender washer on either side and a wing nut. I go hand tight. Once it starts to pull the step plate against the mast I'm happy. A lock washer might be a good idea. I dont have one but It couldn't hurt.
If your spreaders are installed as mine, the bolt will have an aluminum tube sleeve that goes through the mast on one side but cannot come out the other because of different hole sizes. The purpose is to keep you for tightening the spreader nut too tight and depressing the mast at that point. So you can tighten it pretty good without hurting the mast. I would use a nylon insert lock nut at that connection.
As mentioned earlier hand tight on a wing nut is fine for the mast step pivot bolt. I use nylon fender washers between the mast and the step sides to keep the step from deflecting and to make the mast pivot more smoothly. Ignore the text on this pic, it is for the mast raising system I made.
(http://i1007.photobucket.com/albums/af200/brackish_photos/Solo_11.jpg)