My experience:
As others have pointed out, this is not a technically challenging or difficult job, just hard because of the limited access to the hose clamps on the engine side of things. I initially tried to seal the tank with JB waterweld but this did not work for me. I finally bit the bullet and bought the tank from local dealer (should've bought it from Sunset).
I used the instructions published here:
Link. I think it took me about 4 hours total.
Probably would have been easier with a hose clamp tool. I didn't have this. I used a long curved needle nose plier.
To answer some of the questions:
My new tank also did not have the hole for the oil dipstick so I drilled that out first, very easy.
It is a good idea to just drain the coolant first because it will make refilling easier and particularly purging the system of air at the end.
No matter how hard you try (trust me) you will not be able to get away by doing this all from the trunk side only, you will have to get a hand or tool into the engine side to release the clamps. It's not a matter of replacing the hoses (I did not), but a matter of releasing the clamps and hoses from the coolant tank. I would suggest replacing the clamps with screw type clamps while you are there.
I also did not buy the ridiculously expensive Porsche Coolant. I used Prestone Extended Life.
Good luck!