iFriends recommends that you use EasyCam Plus because it makes better use of available CPU and memory. SuperCam is a stand alone application and requires you to download extra software. Prominent placement on the site is not determined by the type of hosting software you are using.
Yes, EasyCam Plus is capable of running multiple sessions provided that you have sufficient upload bandwidth and CPU capacity PER SESSION/SCREENNAME. Please refer to the above question "What are the requirements for each quality setting?" and multiply the bandwidth required PER SESSION/SCREENNAME.