on my Bezzera I fill to a mound, lightly tap 3 or 4 times on the bench, level off and tamp lightly. While I do aim for about 25 sec, Id be watching mostly for signs of blonding to pull the shot at that point if it happens before the 25 sec.
I use a mix of grind change, tap on bench change or tamp change to adjust for different ambient temperature or humidity. However, having said that, Id advise you to go for a medium tamp, a polish/twist with the absolute lightest pressure and adjust the grind. If I take the p/f out straight away the top of the coffee puck is sometimes a little wet. Big question (and the right one)- how does it taste?
The tube you are talking about is the drain from the 3-way valve which takes pressure away from the grouphead so you dont get that great explosion of coffee from the p/f when you remove it!
Bezzeras are very capable and forgiving machines- itll all be fine.