a) You need to move your hero next to the guy with the ? / ! quest marker in order to be able to talk to him.
b) When out of quests, just build a small raiding army and go farming the map(s).
(I use three archers, three archer/laborers, and usually a half-dozen melee and/or cavalry units.)
To go farm, click on your home town, create an army, select the army, right-click on a town (ideally one which says "Trade"). When a magnifying glass icon appears, click that. Now kill some enemies (green on the map for some reason), and watch out for moving enemy armies (red + icon on minimap).
After the fight, have your archer/workers loot the bodies.
When you leave the map, your army will have arrived. Sell excess stuff if you have any, repeat.
To recruit mercenaries, either trade in a friendly town or setup a tent camp to buy mercenaries (even from the other races, depends on which region you are in).
When your army returns home, move all the gold back to your city before - do so before logging out, or the army will consume the money. Enter home town, click "get crowns", buy them for 4000 each.
I found this easiest with orcs with the Looters trait - I kept hitting the resources cap for the army because of all the food we "found" (Elves have the advantage of only looting gold).
Here's a suggestion for exootic places to farm at: