How/when to formally ask for acceptance?

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Hi all,

I am in the process of applying to an M.S. program in a bio-related field. The program in question requires that applicants secure commitment from a faculty member to serve as their committee chair (in which case the student will work in that faculty member's lab) to gain acceptance, ideally before sending in the formal application. I recently had a campus visit to the department during which I met one particular faculty member who heavily implied throughout the visit that they would be willing to accept me into their lab, although it was never outright said. I later emailed the professor to thank him and let him know I plan on following up with him, and he said he looked forward to following up with me and provided me with his availability schedule for the upcoming months. I am very interested in working with this professor, although I am waiting to hear back from other faculty members who I am also interested in working with as well (I emailed them 2 days ago). The lab I am in will probably significantly affect the kind of work I will be doing, as these other professors are actually in a different (but related) department that offers the same M.S. program.

The problem is I'm not exactly sure what to write in my follow-up email to him. It seems a bit silly to send the usual email asking if there are any openings in his lab as it seems to have been made pretty clear that there are openings and that he would be interested in having me in his lab. Also, should I wait until I've had enough time to be fairly sure the other faculty members will not reply? I' don't want to give up on the chance they might reply, but I'm nervous about this opportunity disappearing while I wait. Finally, when would be the appropriate time to ask about potential funding opportunities - bearing in mind that I'm not likely to receive funding in this lab given my background and what I've heard from other grad students about lack of funding in this lab?

Thanks!