All Trade Machines GUI for Edit Trader's Trade Rules -
Currently the GUI is a bit confusing. Making it where you can open the trade rules and just see the start screen that currently shows "Sales,Blacklist, Player Trade Limit, Whitelist,Trade Limit,Discount, free samples" and when you check mark/turn on one of the features the tab for that feature will appear instead of them all just being present when disables or enabled.

Free Samples for all Trade Machines -
Free samples currently operate where you turn it on in the trade rules but if a machine has multiple items you only get one free sample and all the other items in the machine don't allow you redeem free samples. (Example, Armor Display has free samples turned on and a full set of starter armor. I chose the helmet for my free samples and it wouldn't let me claim any of the rest of the armor, it went to charging.) so adding where we can maybe choose which items in the machines get free samples or just allowing the every item in the shop to give a free sample.

Player Trade Limit per Trader -
Currently if you set the player trade limit in the trade rules it applies it to everything in the trader. giving us the ability when setting price to set trade limits per item would be better. Maybe turning the option on in Trade rules, then returning to the item where you set price would now have a option for trade limits, but if the Trade Rule for Trade limits is off there is no option present.

Create mode for traders -
Currently if you enable creative mode for a trader it shows a RED X over the C. This to me indicates that the Creative mode is disabled but currently the RED X means that it is enabled. Changing this would make it more clear. Where as the C without X means enabled and the C with the RED X means disabled.

All Trade Machines GUI for Edit Trader's Trade Rules -
I agree that seeing all of the tabs can be a bit confusing. This is admittedly a recent change, cause I wanted to rework the trade rule system slightly so that you can "disable" a trade rule without losing any data (such as a whitelist rules player list, etc.) such that you can re-enable it at a later point.

That said, I have a few possible solutions to this.

1. I could either make the tab buttons for each selection change color (just like I do the background) based on whether they're active or not (green for active, red for inactive), making it easier to tell which buttons are relevant, and which ones you can ignore.
2. I could sort the tab buttons so that the "active" buttons are on the left, and the "inactive" buttons are on the right. If I do option 1, I'll probably do this one as well though.
3. I could hide the "inactive" trade rule buttons. This would probably be the easiest solution out of all of them.

Free Samples/Player Trade Limit Per Trade -
The reason they work that way is because you're assigning the trade rule to the trader, not to the trade.
If you're on the trade edit tab (the tab where you define the trades price, etc.), and click the Trade Rule button, it will allow you to edit trade rules specifically assigned to that trade (and the tooltip when hovering over the Trade Rule button changes to notify you of this), allowing you to have only that one trade have a free sample, trade limit, whitelist, etc, while the other trades remain unaffected.
You can also, of course, have multiple trades have the same rule but independent memory (so long as they're assigned to the trade itself), such as giving trade 1 & trade 2 a free sample, such that a player would be able to get both of them for free on the first purchase.

Creative Mode for Traders -
I agree that this could probably be done slightly better. What I'll probably do is have it display it's current state (X over it if not creative, no X when creative) when not hovered over, and change to the other icon if the mouse is hovering over it (as a preview as to what would happen if you clicked on it).

Should be fixed in v2.0.0.2 :)