This is my coming-out as a bloody beginner...

Is it possible to open several instances of a vst-plugin. Example: I'm working with Eve and want to use one preset in track 1 and a different in track 2. Is it possible to change presets of a vst in 1 track (like a prog-change)?

How can I add a fade to the whole piece? In Buzz this is very simple: Insert a pattern at the position where the fade should begin and record the slider-movements of the master-volume. But how is this done in EnergyXT?

How can I use a vst-effect only at one or a few positions in a track? Example: I want to begin the drum section with an echo, but want to continue the drums from measure xx without the effect? In Buzz this is very simple: Insert a pattern at the position where the effect should begin and insert the "mute"-command at the position where the effect should end.

ebop, this is a very brief summary , have a look at NicFit's tutorials (www.xt-geek.com)for loads of good info.

Multiple instances of VSTis
Yes, you can have multiple instances of VSTis, either in the main eXT window, or within the Sequencer. I would rename them to indicate what each one is doing. As for program changes, with some VSTis the Patch used is a parameter; if so, then you can map a CC number to that parameter then send CC values to change it. That might do what you want.

Fading Pieces
You could try either of these
a) draw a CC pattern in a MIDI Part (seelct the Cc number you want to use, and set the Snap to 64 or Off, so you can get a fine resolution), send it to the Volume control on a Mixer comp (create the Mixer, Edit -- CC Map, select the CC number you useed in the MIDI Part). Trigger the MIDI Part when needed, form another MID Part

b) use the Envelope comp to create the Fade and send its output to a Mixer volume, then trigger the Envelope from a MIDI Part at the appropriate time.

HTH