I did a search for a variety of terms, but this was a hard question to search. Is there a way to create breakable brushes, like boards that break when smacked with a melee attack? To be honest I can't remember this in any vanilla quake level but I think I've seen it in quake somewhere... 

You can make an brush destructible so that after it takes a certain amount of damage it disappears. It's not very visually satisfying but it's functional. You might have been looking for visible feedback when the object is broken, like little broken chunks to spawn. This is added in lots of mods (including mapping mods like Quoth/AD etc) but it isn't possible in unmodified Quake.

If the very basic disappearing object is good enough, there are two options. The classic approach is to make the plank into a func_wall, create a trigger_once around the plank, then give the trigger a health value and set it to killtarget the func_wall.

It's possible to use a map hack instead, where you set a health value directly on the func_wall, then give it a suitable th_die function. This is especially helpful for creating breakable objects with non-rectangular shapes. If this approach is particularly interesting I can fill the details into the outline. 

most big mods have a func_breakable entity. (for example: rubicon2, RRP, alkaline, AD, quoth.) However, vanilla id1 does not support the feature. 

You can make an object into a trigger_button, set the button speed to 999999 (so it disappears as soon as you shoot it), give it a negative "lip", so it completely disappears when shot. Then you can make a point entity of the type "info_notnull", and give it the key "use" with the value "OgreGrenadeExplode", and a "targetname" that matches the button's "target". This will cause an explosion effect when you shoot the button. You can even make some debris, but it won't be animated. You can make a pile of debris into a door, give the door a negative lip, flag it to be toggleable and flag it to start open (and set the "don't link" flag too). Set the speed to be super high, and give it the same 'targetname' as the explosion, so now when you shoot or hit the button, there will be an explosion, and the debris will appear. 

i'll give some of these a try. 

progs_dump has 2 types of breakables. One is really easy and features 32 commonly textures found in Quake and the other allows you to use any texture you need with a bit more set up.

Also we have func_fall2 that allows you to create spinning debris and similar brushes. None of the func fall stuff is intuitive but I have a sample map in the devkit that displays how it's done.

You can see all this on pages 55 and 61 here:

http://www.quaketastic.com/files/single_player/mods/progs_dump_manual_200.pdf

and more info here: https://www.celephais.net/board/view_thread.php?id=62007&start=0&end=0#0

and this video covers both entities and much more
https://youtu.be/gTbkLP3B2FE 

Does someone know a way to move misc_models like a func_train? I tried it with path_corner and path_rotate but it doesn't work. Maybe I've done something wrong. Want to create some Monsters walking like ghosts in the background. 

Not sure, but one hack would be to make an invisible train (using skip texture, or setting alpha -1) and placing the monster on top of that train. 

Nope. Doesn't work. Seems this entity wasn't made for trains. 

If a static entity has a walk frame, it is possible to use the frames on a position, so that they walk away from the origin.
Placing the same static entity as info_null, it will look as if it it walking from its start position.

It needs some correction in the mdl file for the walk pose, which can be done in an editor. But as the monster isn't used in game it won't matter. 

Maybe instead of using misc_model, you could use a real monster but use map hacks to make it non responsive. That should make it ride the train.

On the other hand, the feature to have misc_models ride trains and plats seems generally useful, so maybe dumptruck_ds should add that. (Maybe a spawnflag on the entity to make it use physics?) 

Version 3 of progs_dump has a way to do what you want I think.

The new entity misc_modeltrain allows you to animate a model and change the frames at path corners. It's pretty sweet. Shoot me an email and I can probably do a build for you. We've delayed the next release by a few months but this function already works. Here's the FGD entries so you can take a sneak peak. 

Thanks for your help.
The hack and the real monster will not work for me because it should walk overhead and turn on path_corners. But big thanks anyway for your interesting ideas.
The progs_dump 3 sound realy good and maybe they will do the effect on to the map, that I thought of.
I'm looking forward to post some screen shoots totday of my project and the map where I want to place this function. 

I forgot to add above what metlslime suggested above is in version 3 already. misc_model now has spawnflags for solidity and physics. And a bunch of new animation options.

spawnflags(flags) =
[
1: "Gravity" : 0
2: "Solid" : 0
4: "Back and forth" : 0
8: "Only once" : 0
16: "Play count times" : 0
] 

That sounds realy interesting. Looking forward to see this in action. 

If I make a map using TB I can export and edit it in Jack, but can't do the opposite. Why? 

First, did you export the map from Jack as a .map file?

If so, you might be using an older version of TB that defaults to opening non-Valve 220 formatted maps. If this is the case, just switch the dropdown from Standard to Valve when opening it in TB. 

And if dumptruck hasn't correctly guessed your issue, you'll need to describe the problem you're having in more detail so that folks can help. 

Violent Rumble have weapons from rogue and hipnotic, monsters from Quoth and features like dp_200. Is it possible to make something like that without any coding? 

I just want to use jumpmod's boots with dp_200 in QS. 

no, you can't combine mods without some coding. You'd need the source code for each mod, and enough understanding to know what files to edit and how. (Also, Quoth source code was never released.)