It's the first time I build a wheel (3 cross) and I would like to use these components:
When I insert the spokes they go in easily, but when they reach the end of the "J" part, they get almost stuck (they can be moved by hand, but they stay in place instead of falling). I laced them anyways and the spokes are quite bent.
Should I choose a type of spoke with a longer "J" part?
It sounds as if the holes in your hub are close to the 2mm size of the spoke. This is fairly common, and the way I deal with it is to slightly bend the spoke while I'm lacing it. The goal is to get the J bend to be slightly more than 90 degrees, but normally what you actually get is a slight bend about 5mm past that. It will be hard to do that once you have the spokes attached to the nipples.
One possibility that doesn't apply in your case is the hub being finished with alternate holes countersunk on opposite sides, but the picture I found online of your hub does not have this.
Since you have managed to lace the wheel anyone the spokes should pull straight when you tighen them up (assuming you have laced the wheel correctly).
I highly recommend Jobst Brandt's book on the subject. It's short, dense, and has a good index. It should cover your concern, it's slightly old so has little on disk brakes and motors but the basics are there in detail.
https://www.goodreads.com/book/show/733514.The_Bicycle_Wheel
