Well, there is a very well done tutorial in Praetorians, so no need to be an expert of RTS to play this game. For the difficulty, there a three choices : Easy, Normal, Hard. You can choose the difficulty before every mission.
The only ressource you have to worry about is the population of your village(s), which allows you to recrut more units, and the only building you can build is the defense tower.
For the record, I'm a C&c and Starcraft fan, yet, I love Praetorians. Once you get used to the gameplay, it's a real pleasure.
Hope it helps :)

Yes, it helps a lot!
Thank you very much for your answer. I think I'm gonna give it a try.
Merci, c'est sympa. ;-)

I reccomed two things before you buy ANY game:
1. Go onto Google, and try to find a free PLAYABLE downloadable demo of the game.
This will at least tell you if you would hate the game. If you love the demo, you cannot count on the game being any good.
2. Google the name of the game with keywords like "sucks" , "crashes", "bugs", and
"problems" to see if it even WORKS at all. Many, many, many games do not actually
work, because they were not adequately playtested, or the company is headed by ripoff scumbag thieves.
3. If you want to try out RTS games, make SURE your computer specs EXCEED the minimums........lots of units in RTS, and this requires LOTS of RAM.
4. If you are not good at RTS, look for games that allow you to adjust game SPEED, not
just difficulty. "Original War" is a good example.
Game manuals are almost always worthless. Google for fan-made walkthroughs.