If you are going to restrict the site to friends why cant it be a members' web site with the member paying a small fee to join the club and gain access to whatever it is the club has to offer to paid up members.
As to the general question of taking people on "experience" flights etc I would be very wary indeed. Its fun to cost share with other pilots and people who are properly friends. However even doing this can impose pressures on you that you actually might find you are not ready to deal with. It can be very tempting to depart into weather that you wouldn't otherwise, or press on in more marginal conditions. There are good reasons for a CPL being a step beyond a PPL and more good reasons if it becomes a commercial op to meet the AOC requirements. I don't think that is a bad thing.
Are you sure you are ready to deal with those "pressures" and have the experience to know when to say NO! Just a very polite question.