Ok, wait.... who is this?

[Anonmon]

Indeed many things in the series left questions open, and so was the end not satisfying too in my point of view.
Takato smiled as he looked into the hideout, where Guilmon was. Why the hell did he do that? Did Guilmon return? Was there the door to the Digiworld open again?

Back to the topic, same goes to Alice. Indeed there is a lack of information about her. Who was she, and how did she act? Many questions which might be interesting to know aren't answered. That's the part I have to criticize (spelled?) at them too.

To answer your first question, YES a Digignome had created a new portal in Guilmon's old home.