Greetings from a noob with an '07 Cayman base,

Bought this 81k mile car on the 7th, and since then my yellow TPS lite on the tach has been joined by the yellow check engine lite, and then the red lite that looks like an exclamation point.
From the owners manual i learned that the red lite is to signify service is overdue or that a particular service is indicated, and if I understand correctly that it can include the malfunction of the tire pressure system.
Seller had an oil change and all new brakes installed at 80k miles, but I did not find out if that was part of the 80k mile service recommended by Porsche. They did mention that TPS sensors were not replaced when the current set of tires was installed, so I expected the TPS yellow lite when I test drove the car (the other Cayman i test drove also displayed this lite and the owner said he would not get them repaired/installed).

When the ck eng yellow lite lit, I stopped by an Advance Auto and had the codes read, and I think they were P0421-31 for the exh/catts and/or leaks. Searching this site and Planet9 I noted that some posters say this code can occur is bad gas is used, or that the car should be driven briskly as intended and it should disappear, which it did but returned after the next fill-up, or even that the fuel or oil fill caps were not on tight enough. My fuel cap appears to fit correctly, and climbing under I found the exhaust system to be in very good shape as this was a VA car and garage-kept by the previous 2 owners.
When I removed the oil cap there was no suction, so i do not suspect a vacuum leak but am new to Porsches. Now, when I used the stalk to flip thru the errors, all I see is service needed. Finally, that red exclamation point lite illuminates (though NOT flashing at first; manual says to stop immediately if it does) and stays lit after I flip the stalk to review, and so I am wondering if it signifies a different problem from the OBDII codes or just backs up the yellow CEL... I know 'winter' fuel is being sold here in MD now, and wonder if this is a a fuel problem. Ran a bottle of Techron before the CEL went out, but it came back on later.
I keep studying the owners manual, and have searched these forums but have not found any answers nor advice, so I thought I'd make this my first post here. Will an OBDII reader clear these codes, or must that Porsche tool be used? In a few months I must smog the car, but these lites should not effect safety insp in MD...

Otherwise the Cayman is an utter joy to drive and I am very pleased! I have no drivability problems that I can discern, but wonder how to address these warnings, or if they're false how to get the lites off. I want to be careful with this dream car I've waited ~40 years to obtain! I am getting ~26mpg with mixed commuting/highway/burn-up-the-back-roads driving, and the engine winds up clearly and smooth (I've had many sportscars, but only my Alfa 164 ever sounded this good!).

Any advice, ideas or comments are appreciated. Be gentle, I tried the search

Thanks,
Mike