It's no problem, and the way I see it, you may not need to, unless you need to use Pallette 6 for a different pallette each tileset. If you have a spare pallette, you may use it for some common tiles as long as you keep the pallettes exactly the same between the tilesets.
Oh...
Then I suppose your post was drowned by the number of new posts which were easy to answer by others...
If you feel like your post was ignored, you are allowed to repost it, though.
I wanna help but I have no idea about what you are asking... =/
It determines the type of message I believe (been a while). For example if you wanted a yes or no message the 0x2 would change to another value.
There are 2 textboxes that I'm aware of, Signs and Talking boxes. The green in emerald is the normal talk box, whereas the gray one is the sign. Yes the value after "@identidifier" does determine that. You should check out a quick tutorial of what the actualy values are.
I know there's a behavior byte that only allows the player to access a block if they're hopping but I don't know about just wheelie-ing. It's definitely possible but yes, it would require some ASM, though it would probably just involve modifying the code for the "hopping" block to check if the player is doing a wheelie.