One thing I have learned is that when converting stem plants from a submerged state to emersed state, it works well to lay the stem horizontally on the soil. it will send down roots and then new emersed growth will start growing upwards at the nodes where the submerged form leaves were. Using this method, it is easier to keep the stem from drying out during the initial conversion because the whole stem is in contact with the moist soil. It also rewards you by turning one stem into several.
Clear lids- I have found that using huge rubbermaid containers with clear plastic lids is the way to go. Cheap, keeps the humidity high, and seem nicer than a lot of the other options. Saran works but it is temporary and a real pain to work with.
Best of luck! Feel free to PM me with any questions. I am not an expert, but I have learned quite a bit in the past year (currently have two set up).