A:AnswerIt turns out it is normal. The online instruction manual does not mention it, but the manual inside the box stated it quite clearly that the vent fan comes on anytime the microwave is used, not just when you wish to use it. It simply doesn't have a separate cooling fan for the electronics like most microwaves. I ended up returning it for a different model.
A:AnswerWell I think it depends on how hot you want your drink. I put the cup of water for my tea for two minutes. You can lower to low med and high but it just as easy it put you cook time in.
A:AnswerNot included with the microwave, but the instructions and materials do have these kits described and you can order or buy them. I reused the ones I had from my old microwave, they are not load bearing and don't actually do anything besides fill in the extra space. I took mine down and cleaned them while doing the install, then put them right back in.