There has been quite a bit of research surrounding mindfulness meditation for a couple decades now.

Here are some cursory studies addressing your three questions. They are easy to find on Google Scholar.

Decreased stress and anxiety http://online.liebertpub.com/doi/abs/10.1089/acm.2010.0142

Increased Focus (specifically for people on the ADHD spectrum) http://www.ahc.umn.edu/img/assets/20825/MindfulnessADHD-Zylo...

I have to imagine mindfulness is a difficult concept to disentangle from meditation itself, however there do seem to be attempts to create measures for this: http://journals.sagepub.com/doi/pdf/10.1177/1073191107313003

Here's a meta-analysis summarizing many studies about the effects of meditation. Effect sizes seem consistently positive albeit on the smaller side: http://link.springer.com/article/10.1007/s12671-012-0101-x

No, there's a ton of science on the benefits of meditation and mindfulness in treating stress, anxiety, depression (where it is as good or superior to any medication) as well as ADHD, drug addiction, etc. It's really a shame that American/Western culture denigrates meditation/mindfulness as "hippie dippie shit" because it is an astoundingly, life alteringly powerful life skill that absolutely everyone should learn.

Is your question addressing QuietKit or meditation in general?If the later the results, some of which you have mentioned, are definetly not purely anecdotal see:https://en.wikipedia.org/wiki/Research_on_meditation

My money is on yes, unless they've developed a unit of measurement for focus and mindfulness which seems unlikely.