Don't be afraid. Every opening line has gambits which can be employed. But as knowledge is power, one is not entitled to be scared. Or I'm wrong?

This offcourse depends on the rating of the players My rating is 1331 (altough i play around 1800 level)

If you have problems against 1...f5 maybe the staunton gambit can be a good option: 

1.d4 f5 2.e4!?
- The cool thing about is that it is only a temporary sacrifice In all variations you can get your pawn back (if you want).

1.d4 f5 2.e4 fxe4 3.Nc3 Nf6 4.Bg5
-Also the move 4.f3 is possible altough after the strong move 4...d5! white has nothing in my opinion.

Here black has two options 4...Nc6 and 4...e6 4...d5? is not possible because of 5.Bxf6 exf6 6.Qh5+ g6 7.Qxd5 Nc6 8.Nxe4! when white is already winning. Some black players may also play the strange looking 4...e3 Against this the best is probably 5.fxe3 when 5...d5 still isnt possible. 

4...Nc6
This is the best move for black.
5.d5 Ne5 6.Qd5 Nf7 7.h4!? 
-White has some space advantage in the centre and the kingside. His d5 pawn can get weak though.

4...e6
This isn't very challenging.
5.Nxe4 Bd7 6.Bxf6 Bxf6 7.Nf3
-White has easy development for his pieces.

It may not suite every player here but some of you might like it. Especially in speed games this is a very good suprise weapon

Thank you for your opinion, I think I will buy the book. 

Does Kindermann still give his d6-e5 idea against the b4-system?
There was a Bundesliga game in 2007 where he suffered badly against Dautov, though he managed to draw.
I think the lines with c6 are more promising for black, there are some games by Nijboer.

I'm toying with the thought of buying the english edition of Kindermann's Leningrad book, although I posess the german one.

Is it worth it? It seems that the english edition is revised and there are additions and new analysis in many places (e.g. the Atalik-Kindermann game that was played after the german edition came out in 2002). 
Is there anybody who owns both editions?

Against the dutch i play the b4 systems. This brings play into positions black players probably won't have prepared as much as mainstream theory. Besides, i think that dutch is ok in main lines but may suffer better  in sidelines...
I found some good ideas in the b4 systems in a post on this forum and on the chessoub database.

Yes, but not the mainline Dutch Leningrad..

I'm not sure why someone would think that analyzing a mainstream opening position with an engine would be likely to help understand possible plans in such a position, much less show "how to beat" one side or the other.  But I get the impression that there are many people who do think something like that.