This does sometimes happen, although these are only present in the editor, and can have things painted over the top of them. In short, although the graphic model still exists, just ignore it as it only exists in the editor as a model. You can add trees, rivers .etc. over the top and the game treats them as if they don't exist.
They can sometimes get in the way of buildings. If you really want a building there though you can play the map for a second, make a save and navigate to your saves folder. find your save and convert from a sh2 file into a s2m file and then move it into your maps folder. All the carts should be gone.
Save game conversion can be very tricky and so it's best to practice with it before breaking your map. Try to only do conversions on maps with NO script or only script that will setup your new save and be deleted later. NEVER convert a map save that is still waiting for a delayed trigger, or ANY trigger, but especially the delayed ones.
Try to limit the amount of save conversions you make to a minimum.
As far as I'm aware, unfortunately not. I don't think there is any way to get invading knights to use a horse unless they are modified from a campaign chapter which does. Though I am astonished that this functionality isn't added into the game editor.
"AI Troops Retreat" is the way I would get around this. I can't remember the mission you are referring to here too well, but I suspect that the knights you're talking about are already on the map from the start. They will start on horseback and be set to an aggressive stance. They can be told to retreat (or just move) to a map marker along with ALL other troops of the same faction (except the Lord). After that event has occurred if the AI is still active for that Lord then he will continue to recruit new troops and not throw them at the marker. So an invasion form the same point that already has knights waiting for the army to arrive, along with an AI Troops Retreat event would most likely work.
Could you describe exactly how you're doing this, what process you're following and all details such as event markers and estate colours so we can try to replicate this?
Sorry, I can't find a way to remove that last quote!
3. I can't be sure here, and may only be partly correct if at all, but I think that the AI swaps the characters around somehow within the map. So now your old castle is actually the Lord you conquered or perhaps even Sir William. So, with the same trigger that switched your castles, make a new event that has a delay of +1 and "Convert Enemy Castle to Estate". I would try the Lord you switch with first, failing that it will be Sir William, who you can now script to become your enemy to capture the estate.
A. Perhaps the 500 gold is already in the treasury of your new castle? Make sure all estates begin with nothing, and try to limit the AI's ability to acquire funds before you get there. An active AI with a treasury WILL tax the people and acquire funds, so if the map doesnt need an active AI then disable it. If you want the AI to recruit new troops then don't give him a treasury and limit his build space. The AI will use any gold that you might want to give it to recruit troops and spend at the market (so don't give it one). You should be able to balance it so the gold has all been spent before you get there.
B. I don't encounter this bug too often myself, but the castle switch is most likely the issue here.
Unfortunately, in some cases, such as custom messages and other things in the Peace Campaign, there is no way to create this in the game. You can only use existing campaign maps and unlock them to use their events instead. This is a pain, but unfortunately there is no other way of doing this that I'm aware of.
Only thing here is to use "Control Number of Estates" and build the map accordingly.
If the lord is a built-in Lord (e.g. Olaf) then you can change their appearance by renaming the .uni files. If the lord is not a built-in lord, such as Duke de Montparnasse, you must edit the appearance of your own lord which will also change them. There is no other way to do that.
In terms of renaming lords, all game text is found in the file C:\Program Files (x86)\Firefly Studios\Stronghold 2\i18n\en.xml. All Lord names are also in there, so you can change them from there.
I'm sorry to say that we don't currently have a tutorial on doing that, but you simply edit the XML file and run the game again, which should show the new text. Though if you have any questions, I'm more than happy to answer them.
There is a way, but it involves converting save files. If you basically want Olaf in a green cape then you need make Lord Barclay where you want him.
Make your map as complete as possible. Begin playing. Save. Convert. Load in editor. On the map overview, change Lord Barclay's Castle Estate into Olaf's. Save. Play, Green Olaf
Can't delete again...but the last thing gets around this.