I'd recommend compiling your own server.
Also what do you mean by rescaling objects, there should be a command in game for that.
As for custom races you need to compile your own server for that can't use a repack because you need to go into the SharedDefines.h like this depending how many races you will be adding
Then you would have to edit:
CharRaces.dbc, CharBaseInfo.dbc, CharStartOutfit.dbc, SkillLineAbility.dbc, SkillRaceClassInfo.dbc, Faction.dbc, CharSections.dbc depending if you're adding custom models or using ones already in-game you won't need to touch CharSections.
Besides all of that you will also need to alter the character creation UI via lua/xml in InterfaceGlueXML you have to add lines and replace lines depends what style interface you're using and how many races you will be adding, you will need to work in CharacterCreate.LUA, CharacterCreate.XML, GlueParent.LUA and GlueStrings.LUA
Once all of that is done you will then need to add in the race/classes to the following: PlayerCreateInfo.sql, PlayerCreateInfo_action.sql, PlayerCreateInfo_spell_custom.sql and Player_levelstats.sql.
So that's all you have to do to add/activate "Custom Races", now... there's an easier way to do it but it's not really adding custom races it's just replacing models with others.
You could just replace I.E. trolls with IceTrolls or Forest Troll models it's pretty simple you don't even have to edit the dbc even though I'd recommend editing it CharSections.dbc but you don't have to just rename the the files of the IceTrolls to what the Troll files are called also this way it doesn't require core editing and there you go.
I might make a guide on here if there isn't one on how to add "Custom Races" any who I hope you understand that it's better to compile your own server then to use a repack even more so if you're customizing.
