I am making a map and I don’t know how many buttons to put into the map. Any recommendations? That would be useful. Also, any recommended water color, because I don’t want the water to be a boring blue/red/green.

i suggest around 4-9 buttons (depending on difficulties)
for water colour it really depends on your map theme, such as desert theme using sand or like poisonous chasm using blue/purple lava

you can experiment the colours and see if you like it