Yes, but it seems people usually put hyphens in compound words only if they are big, if they have numbers (specially cardinal number) or if it's too ugly/ambiguous without them. I think no one uses a hyphen in this word.

kovrilo – cover
tuko – cloth

https://eo.wikipedia.org/wiki/Litkovrilo
https://eo.wikipedia.org/wiki/Litotuko

Litotuko is a bedsheet, or a thin, easily washable piece of material that is used to separate the human from the less easy-to-clean parts of the bedding. It's almost always used below the human, and often a second one on top of the human (although a duvet cover can fulfill the same function here).

Litkovrilo is a blanket, or a thick piece of cloth that is hard to clean and/or wash, and is the main source of thermal isolation from the above (and sometimes bottom as well, it depends on how you make your bed). Kovrilo in general refers to all blankets, regardless of whether their intended use is bed, chair, or grass (piknikokovrilo).

None.

Not really, "devas" is more like the verb "must" in english, and while they are interchangeable in english, they mean two different things in esperanto