I have never used the Powersun make of MVB myself but I think many people do. As long as they're not coiled or looped it should be OK, but hopefully a user of Powersun will be along and can tell you more.
I just use the one bulb for the 3 essentials rather than a tube.
They will work without a hood but the advantage of a wide dome hood/shade is that because heat rises, a dome will direct the heat and light to where they are needed. Some people think the deep domes cause bulbs to over heat and burn out more quickly. You can buy them quite cheaply in places like Home Depot I believe, (if I remember rightly they are 'broodesr' and cost about $10) if I but I think it is recommended the wire guards are removed from it. If you do a search you may find a recent thread about it.
Welcome from Las Vegas! I'm on my second winter using a Powersun MVB bulb. Once I found the proper height for it, the light has worked with no issues. If I remember reading the instructions correctly, it does recommend that it be mounted vertically in a ceramic socket (something to do with the Mercury I suspect).