Ok, i had a brief inspiration cycle while in school and i doodled something reminescent of a plan of a megaproject, now i like to call it the hanging gardens(altough it will probably be underground).Now what i plan to build is a big chamber that is higher on one end and has water coming trough to the other side(preferably if i could make it somehow dissappear into a chasm), there will be statues and waterfalls and two(or one depending on the version) paths that will go trough the middle.Now, i could porbably find the answer to my questions on the wiki but seeing that my internet has been slowed down horrifiyingly by the provider i would much prefer the answers in one place.
Now for the questions:
1.Pumps, i plan to use pairs of pumps, will it be neccesarry to power them both separatley or can i just place them next to each other and power only one?
2.When water muddies ground that was previusly bare, say obsidian cave floor, will anything grow on it, now i don't mean farming, just ordinary grass and shrubs
3.If i open the roof to the outside what plants will grow inside, aboveground ones or ug ones(i have an ug river somewhere just have to find it)
4.Can i get sand from caravans, if yes which ones, i would really like to encase the path in glass so the dwarwes can admire the room without being endangered by the stuff outside