is there a difference between lifting with more speed or less? like bench press as fast as possible or go down slowly and lift up slowly?
Yes, it targets your fast and slow twitch fibers. Your fast twitch fibers are used when you push the weight up and slow twitch fibers are used to control weight as you are lowing the weight down. You benefit more if you lower the weight in a controlled matter( about 3 or 4 seconds) and when pushing up the weight, you should try as fast as possible in a controlled manner to push the weight back up.
I don't really know what you mean by this.Remember there are two types of fast twitch fiber so using faster or slower lifts will isolate the different of the two fibers.
General Rule of Thumb:
Fairly-Light Weight Very-Slow (5-10 seconds one-way) Builds Strength & Endurance (& sometimes Size as well)
Moderate-Weight Semi-Slow (1-4 seconds one-way) Builds Size & Strength
Moderate-to-Heavy Weight Fast (<1 second) Builds Power & Size
"Isometric" (strong, static contraction held for 7-to-12 seconds) builds Strength & Power/"Springiness" (& sometimes Size as well)