chia--to answer your question, no everything can buy certain biomorphs, but its limited to what unit type it is. for example, you cant give a gaunt scythed tail. also, you cant give everything every bioweapon, so no more gaunts with venom cannons or things like that, only spinefists, devourers, and fleshborers. no more hive nodes either, certain units are synapse creatures and they have to be within 12'' of those. the synapse creatures are hive tyrants (duh) broodlords (uber genestealers) warriors (also duh) and you can buy the synapse hive mind power for zoantheropes. you can look at all of the updates
here