Does this work on just PC or Mac or both? Both. It is an Adobe Air application.
Will I get updates for free? Yes, update with one click when a new update is released.
How many computers can I use this on? If you get the light package, only 1 computer at a time. If you get the standard, 3 simultaneously. If you get pro, no limit.
Will the software still work if I refund? No, your license key(s) will be deactivated if you refund.
What if I already have software that extracts member ids from FB groups? Group member id extraction is just ONE feature of Social Lead Freak. It also lets you search for groups, before you extract members of the group. You can also search events and extract ids of attendees of events. Social Lead Freak is also much more than just a member id extraction program, it allows you to search posts, pages, places, people, google+ activities, filter, sort and export the data.
How do I upload the csv file that contains UIDs to FB and target them with FB ads?
Check out this training video on building custom audiences with SLF
You can even convert the ids into Facebook emails!