Ticking and burping noises after valve cover gasket change and radiator issues

I’m a first time driver. Got my (first and only) car, an Acura 99 TL, about 8 months ago with 155k miles. I have driven it for about 9k miles now. Had no issues whatsoever, except for an occasional air-filling sound from the glove box, which I chose to ignore since the car didn’t have any other signs of trouble.

4 months after I bought the car, I changed the spark plugs because I had vibration on idle. Fixed. 2 months later, my car needed a new valve cover gasket. Did that myself, changed the fluids after the job and cleaned the EGR valve and throttle valve. Ever since the gasket replacement, I’ve had problems. On the bright side, the RPM settled on idle from 1000 to 800 and gas economy has improved.

There we’re no strange noises after I did the gasket except for a constant, low ticking. I don’t know if this was present before. I changed the oil 3 weeks after the gasket replacement and these ticking sounds have reduced somewhat but not fully.

The radiator started to lose fluid after the gasket repair! I could notice steam from the hood occasionally. Since I would only lose very little fluid overnight, I just put in some sealant. Did that in 6 or 7 steps using a small bottle before emptying the 1 quart bottle of sealant. I don’t lose fluid now. On the contrary, I notice the reservoir gets full. I have checked hoses from radiator to reservoir and they seem to be okay.

At times, on idle, the car kind of wants to shut down but doesn’t. Kinda loses power for a second or two, hesitates then returns to normal. I have had occasional white smoke coming from exhaust in winters (I live in North of Florida) mostly from a cold engine. The car does not overheat (I haven’t driven long enough, though). The engine oil level is okay and not milky. One spark plug’s screw broke off during the gasket replacement. I put the spark plug in place and then taped it (it does not seem loose).

Moreover, there is a strange knocking or burping sound coming occasionally while idle. It shakes the car and travels to the back. I recall the knocking-type sound came after I used a syringe to take coolant out from the reservoir to put it in the radiator. Did I introduce bubbles in the system? Is that why I have that strange knock?

What else could be going wrong? I need to make my car last another 4 years. I’m a PhD student and that’s when I expect to graduate.