Around the luggage compartment under the hood are water drain channels. These are pretty shallow and if they have gunk in them the water will overflow and can get into the luggage. Make sure you keep leaves and junk out of them. On each side of the battery are little water drain holes to get water away from the battery. Again leaves and junk can easily block these holes which then causes the "brake booster" to suck in water. Check them every so often to make sure they are not clogged.
The oil pressure gauge seems worthless at first (because the oil temp is easier to read and they are semi-redundant), but actually it's the best way to check on the health of your engine and know when it is ready to thrash. When you start it up, it should read around max, 5 bar. Once the oil gets loosened up and is flowing right, it should settle in to about 1-2 bar at idle and 3-4 bar at high RPM. If it doesn't get up to 3-4 bar once warm at high RPM, you have an oil leak. My next oil change is going to be to 5w50.
There are a few known design flaws with the car (aside from the RMS/IMS elephant in the room) :
They seem to be prone to premature serpentine belt failure. This is not a huge problem, just something to be aware of. Changing the serpentine belt is very very easy on this car, like most of the minor maintenance. All you need is a 24 mm wrench. Take a photo of the belt routing before you remove it so that you can replace it the same way. The tensioner is self-adjusting, not manually tensioned, so you don't have to worry about tightening it right when you put it back on. One reason for failure seems to be that the pulleys can wear grooves . I would replace every 30-40k miles instead of the recommended 60k.
Another is that shift cables can break , particularly under heavy use. This is also pretty cheap to replace, though not a DIY, and obviously inconvenient if it happens out on the road. Generally the transmission is very "notchy" and heavy, which is cool and by design, it is meant to be able to handle a lot of torque to quickly shift and get power through. The syncros in the transmission that help you rev match are pretty minimal and hard, that is you need to rev match pretty well or they will balk, unlike a lot of comfort cars where the syncros are very forgiving and let you shift even with a bad rev match. The problem is if you are trying to jam the transmission without rev matching well enough, it puts heavy loads on those cables and they can't take it. Even if they don't break they are prone to get out of adjustment, particularly the 1st/2nd gear clutch control.