I recently bought a Contessa 26 too! On my old Farymann (a K30 I think) the dipstick is on the port side of the cylinder head area. I've found it almost impossible to check from the access panel under the stairs in the cabin. So the alternative is to open the engine access cover in the cockpit. My boat has a smaller access panel directly over this area which can be opened easily. Once opened, I can reach in with one hand to pull the dipstick up and then looking in from the cabin side with a flashlight, I can see the oil on the stick--much easier than removing the whole access panel. Although you may wish to open the full access cover to do an in-depth check before running things up.
I can't remember exactly where the oil goes but you can find a scanned in copy of the manual here: https://www.manualslib.com/manual/10109 … -K-30.html. Next time I'm out at the boat I'll double check and let you know.
I'm also not sure about overheating or oil pressure alarms/indicators. I don't see any on my engine either but I'm hoping it can be something that can be added easily and cheaply! There is something near the starter button in the cockpit that looks like it might be a buzzer or something but I haven't had time to look at in detail yet.
I'm sorry that I'm not an expert on this boat (yet) but I hope this helps you some.