Question about combining a full agonist with a partial agonist.

Really, it depends on the binding efficacy if the partial agonist will displace the full agonist. See buprenophine and heroin.

Difficult to say. Most people will tell you that a partial agonist will act as an antagonist in the presence of a full agonist and that is the answer that would probably correct on an exam. However, I think the whole thing might be complicated with some receptors, especially g protein coupled receptors. LSD might be a partial agonist of 5-HT-2A relative to 25iNBOMe, but this does not mean necessarily that it will produce a less intense psychological effect. This is because G protein coupled receptors exhibit some pretty insane signaling bias. LSD might have a lower binding affinity or is not able to activate the receptor as efficiently , but may induce a confomer in the receptor that has a very high affinity for dimerization or favors the activation of a downstream effector that greaty magnifys the signal relative to what 25i can do. Signaling bias is the reason why all the drugs in tihkal and pihkal produced a huge spectrum of effects and it greatly complicates the whole idea of what a partial agonist is and really messes up rational drug design. We are trying to science out what is going on with drugs, but the mechanisms are so over the top complicated that sometimes it just feels like a guessing game more than anything