Committees sometimes adopt a routine motion such as this one to permit the committee to receive evidence so as not to delay the witnesses, to enable the witnesses to make their presentations regardless of whether there's quorum or not. So that's why the reduced quorum is there.
In terms of the amount of time granted to witnesses to make opening statements, 10 minutes is a baseline amount of time; however, it is at the committee's discretion or at the discretion of the chair, if the committee delegates the chair that discretion, to be able to alter the time for opening statements as necessary. For example, should the meeting be divided into two one-hour panels, sometimes it's appropriate to be able to hear more witnesses to reduce the time. So that is something the committee can amend within this routine motion or can give the chair the discretion to do as needed.