Unfortunately yes, you have to have a tool that can edit and save palettes. The palette will be needed when you load your tiles into the block editor of A-Map.
If there's anything about palette editing that you don't understand, please feel free to leave me a visitor message or private message. I'll be more than happy to help you further.
Paint DOES have a grid. If you zoom in, and then go to View >> Zoom >> Show Grid/zoom in and do the Ctrl+G shortcut, it creates a grid.
Oh wow, I've never seen that before. It's a shame it's just a pixel by pixel grid, rather than a adjustable grid so you can easily measure 16x16 tiles.
It's still usefull, especially for tile making and sprite editing. :D
I'll update the description informing that it does have a type of grid, though.
Thanks for sharing.