It doesn't open! Gabby's Cafe is only for decoration.
To unlock Spinda's Cafe, just get past WATERFALL CAVE for the first time. If I'm not 100% correct, look on Bulbapedia for more info.
You can open a cafe shop much like you would any other business. You must first register the business, obtain the required space, and get all the necessary equipment and personnel necessary to make coffee.
There is a shop at the port, and then there is a shop at the cafe itself right outside the port that is open. The actual restaurant part is not open yet.
The Bull Dog Coffee Shop near Oaksterdam University in Oakland California.
no
yes
The Buena Vista Cafe in San Francisco is open during the weekend from 8am to 2am. If you visit the cafe during the week; 9am to 2am. They are open 365 days a year and open for special reservations.
Yes
Probably not.
8am
August 2009 apparently.