you can't add objects in replays, you only have whatever objects your mods have
you can however make the illusion of an object appearing by having a mod with an object far away and then teleporting it to where it can be seen
for moving objects around you use EPOS, EQAT, EANGVEL and ELINVEL, they work in the same way as POS, QAT, ANGVEL and LINVEL but they have E in front of the name and move the environment instead of tori and uke
they appear as EPOS 0; x y z x y z x y z ... so you always have 0 there and every x y z triplet means coordinates for every object in numerical order by object id
if you dont know how POS, QAT, ANGVEL or LINVEL work just check this thread:
http://forum.toribash.com/showthread.php?t=19742, which also has some information on environment hacking
also there isnt really any rating system, the people in charge of the stock folder just discuss the replays until they come to a consensus