No not at all. The bubbles are in a private farming/forest area. 
When you book you can see how many people each bubble has allowance for. Most fit for 2 adults but in some you can add 1 or 2 people more.
From 9. July we will have 3x bubbles so we can accommodate 6 people – 2 adults in each bubble. This is of course subject to availability.
Yes it is very safe. Around the entrance is a metal frame so the bubble will never go all the way down in case of emergency. The plastic is certified as low-flammable.
Yes in Reykholt we have Cafe Mika. We love their lobster soup:) At Fludir (10 min drive) we have a restaurant at the Icelandair hotel.
At the moment the best way is to simply rent a car and drive there yourself. We recommend 4×4 on spikes in the winter time. We are not yet having our own transfer to the bubble.