I've been keeping Greek's (Ibera, Terrestris, and Soussensis), amoung other species, for 25 years so here's my input to your questions.
1. Alone, unless you have a large enclosure and purely females. Males battle constantly and it can get ugly. If you have a male and female, the males are relentless in pursuing females and it can get ugly for the females. All Greek's are solitary animals by nature.
2. Not if you keep the enclosure free of accumulating poop.
3. Way too small. 3'x 6' minimum for a 5 inch SCL animal. The bigger, the better. These are tortoises that wander far and wide every day for food, shelter, and mates. Lots of site breaks help too. they all love climbing over rocks. They are not like Eqyptian's, who can do fine in a small enclosure.
4. Very much so, once they get acclimated. My oldest male Ibera (25 years with me and an adult when I got him) comes running over where I'm at whenever he sees me coming. Loves to have his head scratched and will let me pick him up and inspect him freely.
www.chelonia.org has a good Greek caresheet under the Care Sheets section.
Good luck.