It's very variable. I check the questions in the morning, at lunchtime and in the evening, but how long I spend on the site depends on whether any of the questions catch my eye.
It can take a surprisingly long time to write a thorough answer, especially since the answers that are most fun are the ones at the edge of my knowledge, so I have to spend time ...
One handy place for this information is the user page of the Community ♦ user, which gives the bot's inception date as 1 November 2010.
For more information, you can go to the original Area 51 proposal, which gives a detailed breakdown of the milestones:
The original proposal was posted on 2 June 2010
Private beta started on 2 November 2010
Public beta ...
As an example of the issue Dirk raises, I'll point to This recent question. Now, perhaps it is not the cleanest of questions, but it did come up today. It was put on hold as off-topic, with comments about how it would be best for engineering or materials. Now, given that it was tagged solid-state-physics and superconductivity (and applies to them), and that ...
MathJax support in tables
test: $\int e^x dx = f(x)$ -- yes, it works! $\Large\checkmark$
Feature requests for MathJax support
Successful! $\Large\checkmark$ (no longer needed)
Unclear -- not explained in this thread
Nature of support requested from this community
Unclear -- not explained in ...
Just take a look at the stats page of each of the review pages (or my 4 Steward badges) and my Marshal badge and you can see how I spend most of my time on Physics.SE (which is also a subtle hint for those with 2k+ rep to start reviewing what you can & those with 3k+ rep to start reviewing the close queue).
I usually spend about 20-30 minutes in the ...
Consider this: if experimentalists are not motivated to post here, where their questions would be well received (given that they are, in fact, about experimental physics), what would make them motivated to post on a separate site which would have even less of a community at first?
Given this I think starting a new site is less productive than trying to ...
I draw my diagrams using Google Draw, then I screengrab the picture and paste it into my favourite image editor (Paint Shop Pro), tidy it up and save it as a GIF. The GIF can then be inserted into your question.
Anyone can start a new SE site on Area 51. However I suspect your chances of ending up with a viable group are small. It take a lot of commitment to get a Stack Exchange site going and I doubt there is enough interest from experimentalists for the site to succeed. Still, you will never know unless you try.