1. How do you get Faculty and grad students to work? Do they get any kind of teaching credit?
This happens naturally. Faculty propose projects and the lab recruits students for the projects (ideally 1 graduate student and 2-3 undergraduates). Faculty meet with teams 2-4 times per month and graduate students meet with teams weekly. Undergraduates have multiple additional meetings. Although teaching release for faculty is nice if possible, my understanding is that this does not occur at most geometry labs (except for lab directors who tend to get some kind of teaching reduction).
Graduate students are usually given some benefit in the way of a stipend or partial teaching release.
What I try to explain to faculty is their benefit is this. If they choose projects that they have a personal interest in, i.e. something they would like to learn about through examples/computations/visualizations but presently do not have time, then the projects are "working for them" through the students' work.
Often enough however, many faculty are already interested in involving undergraduates in their research. So a geometry lab helps facilitate this for them by giving them space to work, technology to use, and student ready to work with them.
2. Do the students get course credit for their work?
This is not necessary as the experience can be noted on a resume/CV and letters of recommendation are a big selling point for students. However, my understanding is that many (perhaps most) labs given undergraduates reading/special topics credit for their lab work.
3. How do you use 3D printers and laser cutters? Do you have an expert in those gadgets?
Basically I tell teams this: "if you can 3D print it, then do it!" The idea is that through visualization of ideas one can help their own intuition and also explain their ideas better to others. Not all projects have 3D/4D visualization available so these are not required of any team.
I do not think we have standing "experts" typically, but instead have teams learn from the community surrounding the lab. The existence of a community is one of the biggest benefits to having a lab. There are many online tutorials too. I find students are very apt at teaching themselves how to use this technology once they understand the math.
4. How are projects chosen?
Faculty propose projects. I usually tell faculty to parse the project down to its simplest example and build from there. Frame the example within the undergraduate curriculum if possible.
Example: At my first lab I wanted to do a projects calculating a specialization of the mixed hodge polynomial on certain families of moduli spaces. So I started with counting the number of 2x2 invertible matrices over finite fields (the first example uses only what Z/pZ is and what a matrix is).
5. What is the purpose of the projects? Publications? Understanding? Divulgation? Other?
The purpose of the project is to further the faculty's research program AND support giving the students a research centric education. This can lead to a publication, exposition, or just further understanding by faculty and/or students. Anyway you cut it, it is a win.
6. Do you have any method to get the software available to other researchers or groups?
GLU wants to foster a central repository but as of yet we do not have one (we expect to have this in the future). Presently each lab is hosting their own.
7. Does the lab owns a physical space at the department?
Yes. Having a physical space the students can call their own is very powerful for them.
8. What would have been useful for you to know when you started your geometry lab?
Have fun. Always put having fun first.