I managed to replace the original digitizer as well. This was my first digitizer replacement and it took me 1 h 45 min the starting point being: this guide open, tools available, replacement part and the smart phone in hand. The operation itself took me some 35 min.
About the screws: I used T4 (I read the comments only afterwards), didn't slip a bit, but T5 fits better now that I tried it.
What a great feeling! I achieved something very concrete today - thanks to you!