Ball screw angular contact bearing block

[dowling177]

I bought a ball screw (http://www.pro.com.sg/ballscrew.htm) it is the 8th item on this page (ballscrew # 1408440), and the angular contact bearings are ones which I have never seen before (when I received the screw the bearings were flipped around the other way so it was flange-bearing-bearing-flange (instead of the two flanges touching each other. The things I am wondering are:

1. should I make a bearing block so each bearing gets pressed into the bearing block hole from either side with these flanges hit the face of the bearing block?

2. you can see that the nut does not screw right down and hit the black part to put pressure on the bearing what can I use to fill this gap

3. how close a tolerance do i need for these bearings to press fit them

4. how much pressure do i need to supply to the nut to put pressure on the two races when they touch?

Thanks for any input and/or help