Can I with one click switch on chorus and delay, switch off the phaser and then control the delay level with the exp pedal and delay time with tap tempo?
You can switch on chorus and delay with one click. Just go to the MOD section, and set CHO and DLY to the same controller number. But you can't switch off the phaser with the same click.
If you store a preset with chorus + delay on, and phaser off, and another preset with chorus + delay off and phaser on, you only need to press one button to switch. You can also control the delay level with the exp pedal and delay time with tap tempo.
The advantage of switching between presets would also be, that you could f.i. assign the tap tempo to the phaser speed, on the preset with the phaser block switched on. You can assign the tap tempo, the exp pedal, and any modifier to different parameters in different presets.
Of course, you can still switch on or off the blocks as you please with MIDI CCs.