The minimum area of a sukka is 7 tefachim wide by 7 long. Less than that is possula. 6 x 9 tefachim is also possula even though there is more area than 7 x 7. (ShA 1 – MB 1)
You aren’t allowed to sit in a cubicle less than 7 x 7 even if it is extending from a large sukka.(MB 1)
There is no maximum area of a sukka.(ShA 1)
A round shaped sukka or a pentagon shaped sukka is kashera as long as you can fit a 7 x 7 tefach area inside it. (ShA 2 – MB4)
If part of your dining table is in the sukka and part is in the house, that’s okay. But if the entire table is in the house, even though you are completely in the sukka, it’s as if you didn’t eat in the sukka. Chazal are worried that you will end up eating in the house although there’s plenty of room in the sukka.Therefore you need to eat again while sitting properly in the sukka. (ShA 4 – MB 6 – BeH “k’eelu”)
The above stated gazaira applies only when you are taking food from the table which is completely in the house. However, if you are eating in the sukka with your sandwich in your hand, not at the table, there is no problem.(ShaH 7)
If your house and your sukka are separated by an area which is forbidden to carry through, you can tell a gentile directly to carry things to the sukka but you cannot do it yourself. (MB 8)