First, you really need to try the demo once it is out to get a feel for the game. It's really hard to put into words because the world is just so massive and there is so much you can do. This is a game that after months of playing, I still had never conquered about half the available world.
This game has a lot of historical events, characters, locations, and cities. Though there is also a good bit of writer's license applied to some of these to make them work in a game format.
I haven't played the beta in couple months, so some things have changed since I last played. The following answers are based on the game status as of when I last played:
1. Is it possible to build upgrades in your cities/towns or not?
Walls and trade routes. City size. Mines, watch towers, and forts outside your cities.
2. Is there a time limit to the game?
3. Will the geographic area to the North of Macedon be available for capture?
4. What are the geographical limits of the game?
All of present day Greece (including islands), western half of Turkey, Bulgaria and a bit into southern Hungary, Serbia, Montenegro, Albania, Macedonia.
5. Will diplomacy be featured in the game, and if so how sophisticated will it be?
6. Will espionage be featured in the game, and if so how sophisticated will it be?
7. Will the player have to contend with revolts, abandonment by soldiers and general raiders and Pirates for that matter?
Revolts of cities, raiders.
8. Are there just available just 3 unit types per group or are there more.
Not sure I understand this question. Unit formations can have unlimited number of units in them (though too many in a single formation tend not to work too well). Formations are custom: you can select a group of units and tell them to move, and they will automatically form a formation, or you can manually shape and build the formation manually out of available units.
9. Will trade be player driven or automated?
Trade is between your cities, player driven.
10. I read somewhere about skill points, what will these be used for?
These affect your troops skill level at various tasks.
11. Do we assign Generals or are they fixed to the units?
12. Are generals recruited, event driven or crafted?
Recruited normally (from an event driven list of available generals).
13. Do generals have traits or skills that make them a worthwhile commodity or are they a unimportant commidity?
Yes, they affect the skill of your troops they command, greatly enhancing the ability of those units.
14. Can a group of slaves be captured by another faction?
Yes, to a certain extent.
15. Can the slaves be ransomed back?
16. What resources will be featured in the Game?
Gold, food, population points.
17. How many settlements will be in the game?
Hundreds, perhaps over a thousand. I never counted.
18. Will AI factions fight against each other as well as against you?
19. I see screenshots of details of seasons, aside from time do the seasons play any other role?
Food production, sheep availability, winter stormy season prevents sea raids and blocks sea trade routes.
20. Will any man made landmarks feature in the game,such as the Mausoleum of Halicarnassus?
Yes. These are used as bonuses to things such as heroism (morale), logistics (food consumption), etc.
21. Will the player be free to pursue his own path or is it mostly mission based?
Both. The demo portion is virtually entirely mission based, but once you are through that, there are quests, but no requirement to follow them and you get to pick which quests to do first.
22. Is it possible to vassalize an opponent?
No. Just go conquer them!
23. Will terrain be an important part of a battle?
24. How will the supply system work?
Trade routes supply food, can be blockaded. Triremes, worker brigades, and slaves can also transport extra food.
25. Is it possible to ally?
Only if a quest allows it.
26. When is the estimated release date if any?