Oil Leak/Burning Smell in Car?

I have a 2012 Honda Civic Si. Early yesterday morning I noticed a burning smell coming from the HVAC when I had the heat on, later that night it became stronger so I checked my oil level; oil needs to be changed and is LOW. I can't get underneath it at the moment so I poured some more oil in for the time being. I checked the undercarriage and noticed that near the filter and drain plug is covered in oil. Any idea what this could be? I d rather address the problem before I have to toss money to the mechanic on Monday.

TLDR

Burning smell in HVAC, overdue oil/filter change, oil leak covering undercarriage, drain plug, filter.

What is the culprit and how can it be fixed?

Added (1). Update: Burning smell comes from inside and outside car, maybe it's oil burning off the engine?

My lights dim randomly at night while driving?

I've been noticing my lights are dimming both headlights and HUD lights. The dimming is mildly noticeable but not to the point their off but annoying.

Any answers out there why?

Honda Civic 2001 DX coupe
(stock)

About reprogramming ECM on my 05 Honda civic?

My malfunction indicator lamp went on just a few days ago. Took it to AutoZone to get it checked out. Gave me a paper saying something about reprogramming ecm. I need help on this matter. My car is working pretty fine and good. AutoZone guy said you won't feel it while driving and I should be okay. I want to know more details about it before I try taking to my dealer.

Car saying Check Tire Pressure?

I have a 2015 Honda Civic SE that I just bought a few weeks ago. I know nothing about cars. My sister's boyfriend already aired up all the tires but the i light is still on and it's still saying "Check Tire Pressure". What is wrong?

Why is a Honda Civic always a car of ridicule in the US?

I often see these cars in memes. Some say its pretty fast in stock form and able to pick at some unsuspecting american fast cars and others say its the cheap choice of Asian home care employees. I'm getting mixed opinions so somebody anybody compare this car with the cars in the US?