I am now totally confused so looking for help.

I own a condo in Thailand and will enter next week on a SETV.

I see conflicting views on whether I need to do the TM30 submission at my local IO.  Some say yes it apples to all foreigners entering Thailand, others say the opposite and that it only applies to resident foreigners.

Supplementary question, I will have some friends staying with me who will come in on visa exempt stamps (30 days).  Do I, as the owner of the property, have to do TM30 for them?

The law is unambiguous that you must do the TM30 notification, both for yourself and any other foreigners who stay in your condo. What is less clear is what is enforced. Some immigration offices are strict that the law on this must be scrupulously adhered to. Other offices are only strict as regards hotel compliance. You do not state where your condo is located. If we knew this, we might be able to give a clearer answer. In the absence of knowing which office you deal with, I would recommend you adhere strictly to the law as written until told by the office that this is unnecessary. The only possible exception is that you might choose not to report foreigners at your property that you know will have no contact with your local immigration office. The penalty for non compliance with the law is currently only an affordable fine.

Yes, you have to do it for both yourself and your friends. You are the owner as well as the tourist staying in your apartment,  your friends tourists staying there. If you all arrive together,  fill the first page for yourself and fill all names (yours as well) in the excel list. Easy and free of cost

The law requires you should in both questions.

But 1) Not all offices worry about this, but as the owner, you should report yourself.

2) If your friends have no need to attend immigration, ie to do an extension, I wouldn't bother.

(Hopefully nobody will bubble you!)