SC2Mapster

You need to go to the "Effect" Tab and create an effect of type "Modify Unit", and then go back to the ability and in the "Effect" field select the effect you just created.

In the "Modify Unit" effect type there is a field called "Experience". So you could use a ability, either "Effect - Instant" or "Effect - Target" to call a "Modify Unit" effect which has the Experience field set to however much xp you wish to give.

I expect that this will work, but I am supposed to be working and haven't tested it.

If it us just the terrain and map size that are a problem then you can change those in the Terrain editor using Map -> Map Textures and Map -> Map Bounds.

By copying each item individually you may break links between different components if you copy them in the wrong order. So just remember to set them up again when you are done.

Its difficult to know exactly what is wrong with the details you provided. When you say it won't let you build do you mean that it doesn't show up as an option, or that it shows up but cannot be selected? If it is the first case then you need to add your structure to the SCV build ability.

1. Got to the ability tab and find "SCV - Build(SCV)".
2. Open up the "Info +" field.
3. Find an unused line and double click on it.
4. In the window that pops up, you will want to select a button(You may need to create one).
5. Scroll to the bottom of the window and set "Unit" to your structure and change the "Time" to however long you want it to take to build
6. Other things you might want to do in this window are add a cost or change the build requirements. Once you have made all your changes click "OK" all the way out.
7. Now go to the units tab and find the scv.
8. Open up the "Command Card+" field and find an open location where you want to place the button to build your structure.
9. Click Ok and the new structure should show up on the scv.
10. Add a new button to the list(the same one as in step 4).
11. Change "Command Type" to "Ability Command".
12. Change "Ability" to "SCV - Build(SCV)".
13. Change "Ability Command" to the name of the button you used for your structure.

If it is the second case then you need to check what you set the build requirements to.

You could store the Old mineral value in a variable, and then in the actions subtract the old value from the current value to get the change.
In this example I have a global variable called OldMinerals.  Just add the actions into the Then or else(The last Set Variable is not in the else statement).  There is probably also a way to do it in the trigger editor, but I wasn't able to find it with a quick look, perhaps someone else would know.

    Events
        Player - Player 1 Minerals changes
    Local Variables
        MineralChange = 0 <Integer>
    Conditions
    Actions
        Variable - Set MineralChange = ((Player 1 Minerals) - OldMinerals)
        General - If (Conditions) then do (Actions) else do (Actions)
            If
                MineralChange > 0
            Then
            Else
        Variable - Set OldMinerals = (Player 1 Minerals)

In the "Modification +" field of a buff behavior try playing with "Damage Dealt (Scaled)" or "Damage Dealt Fraction" I would expect that a value of 1.1 in one of those should give a 10% bonus.

I do not know about fixing the origins location, but the upgrades to an individual tower can be done using abilities that apply a behavior. If you use the ability type of "Behavior" then the button seems to disappear once you have used it. If you want to be able to apply the same behavior multiple times I have found that you can use the "Effect - Instant" ability type and then create a "Apply Behavior" effect that will allow you to stack the same behavior multiple times(as long as you set the maximum stack count to more then 1).

You probably need to duplicate the actor for the Marauder attack as well, either MarauderAttack or MarauderUpgradedAttack and set the impact effect to the modified damage for your weapon.

You could try placing some Pathing Blocker doodads and then destroy them with triggers.

Ok, well that is not nearly as easy as I would have expected, but I believe this will do what you want.  When a dialog item is used it will loop through all the units owned by the clicking player and check to see if the heroic flag is checked, if it finds one it breaks out of the trigger, otherwise it will continue on and then create the unit at the end.

    Events
        Dialog - Any Dialog Item is Clicked by Player Any Player
    Local Variables
        currentUnit = No Unit <Unit>
    Conditions
    Actions
        Unit Group - For each unit currentUnit in (Any units in (Entire map) owned by player (Triggering player) matching
                          Excluded: Missile, Dead, Hidden, with at most Any Amount) do (Actions)
            Actions
                General - If (Conditions) then do (Actions) else do (Actions)
                    If
                        ((Unit type of currentUnit) has Heroic attribute) == true
                    Then
                        Trigger - Stop all instances of (Current trigger)
                    Else
        Unit - Create 1 <Unit> for player (Triggering player) at <Point> facing 270.0 degrees (No Options)

Not sure, basically make sure any changes that have been made were intended.

Just add a condition to the spawning trigger that the player does not already have a hero.

Here is my entry, the Nukekoo clock. It is like a Cuckoo except instead of a chirping bird, it launches a nuke. The clock is running at 20x speed.

In the trigger actions under "Tech Tree" there is a function called "Set Upgrade Level For Player", have you tried playing with that?

I believe this should do what you want:

    Events
        Timer - Every 10.0 seconds of Game Time
    Local Variables
        customResources = 0 <Integer>
    Conditions
    Actions
        Variable - Set customResources = (Player 1 Custom Resource)
        Player - Modify player 1 Minerals: Add customResources