The first one definitely looks like a hybrid to me. It's similar to the Odontaglossum/Oncidium crosses for sale here, but I couldn't find a name.
The second one does look like Oncidium lanceanum to me. Does it have a fragrance? that species is supposed to and might help to confirm/deny.
The third looks more like an Oncidium stacyi.
I agree that the last one is likely not Oncidium sarcodes, but unfortunately oncidium hybrids are so popular there are thousands of different ones. An exact id is somewhat unrealistic. Also, I'm a bit color blind so...
"Oncidiums" is becoming a generic term for most all the Oncidium/Odontoglossum alliance. Tho we are calling them oncids, we are not specifically saying Oncid species by doing so. I think two and three are probably correct, or very close -- like a primary hybrid. The other two appear to be a mix -- likely hybrids.
Your growing will do fine to follow oncidium culture, I think.