1. I don't know of any recent one, but I consider this to be a very good and informed review of the game: 

http://www.gameinformer.com/games/fallen_enchantress_legendary_heroes/b/pc/archive/2013/05/29/building-a-fantasy-empire-from-the-ashes.aspx

Just keep in mind that this review is from back when the game was released, it has undergone some major improvements, especially concerning the AI in the current beta 1.3 build that is all about getting the AI on track. Diplomacy is still a drag but is already sceduled for improvement in the upcoming patches.

2. yes, a lot of fun if you have the time and verve to get into the deep mechanics of the game and tweak them to your liking.

3. no, there might be some new scenarios in the future, as of now the campaign is all you get.

4. sure, if you know your way around XML.

5. It has taken a BIG step in the right direction compared to the release version of LH and especially compared to WoM and FE. There are still some problems and annoyances if you are a veteran 4X player (troop composition, pathfinding, tactical combat), but it gets the job done on higher difficulties and it will challenge you.

6. less random disconnected game mechanics, more streamlined in the champion, traits and city building department. Much more interesting tactical combat due to stronger focus on placement and abilities.

There are two DLCs. The map pack DLC provides you with more premade maps to play on and varied tactical battle maps, the Quest DLC adds more quests, random events and items for your champions. 

This game is all about the sandbox mode where you can let the generator create a random map with costumizable options like landmass, resources, enemies etc. The campaign is basically a glorified Tutorial to get you into the game world, it is not really meant to be played over and over again.

Yes, combat is much quicker now because opposing forces start closer to each other, it is a concious decision. It is an issue if you prefer in-depth combat. To be clear: Legendary Heroes is not all about complex combat like for example in Eador. It is fun and you need to utilize placement and abilities to be succesful, but more refined mechanics like terrain bonuses, line of sight and morale are left out. To draw an analogy: They are quick snacks and no five course meals. Still, I like them because I personally don't like long drawn-out fights with lots of tactical considerations.

In the same vein you won't find any siege combat in the game. Attacking a city is basically the same as attacking enemy units in the countryside just with a different visual background.

Visually, yes, but cities get defenders, and fortified cities give crazy bonuses to defenders. Spells can help defend cities as well.