N1 refers to the rotation speed of the low pressure spool, that is the huge fan whose blades you see when looking into the engine from front.
N2 refers to the rotation speed of the compressor and smaller fans in the deeper, more rear-ended parts of the engine, which are sometimes called the high pressure spool.
In the sim, you check the setting of thrust via N1, it is most directly related to your throttle. N2 reacts with a delay mostly, you check it to decide when to open the fuel cutoff levers on the pedestal, else it is of little interest in a simulation as long as you do not do failures and emergency trainings.
On your altitude, the normal descent path on GS for final approach is 3°, that means that at 15 miles distance to airport the GS is around 5000 ft, and at 10 miles still above 3000. On the other hand you fly at 1400 ft with 10 miles distance to the airport, that is less than 500m altitude! When you finally catch the glide slope, the plane will go into a more or less gentle dive, but in an addon doing this in a harsh, not gentle manner, the plane may overshoot and manouver more hard in the vertical to catch up the glideslope - and this time from ABOVE, because it has over shot. And this with that close vicinity to the ground! Not good.
Final approach charts that have a map for every single possible approach an airport is offering, at the bottom have a profile for the vertical flightpath, the descent, where there are ranges and altitudes marked together with outer and middle markers (vertical NDB giving you a signal when you overfly them). Often there are even more altitude restrictions marked, due to noise abatement procedures or geographical terrain features and high-reaching landmarks. Also, if you use the radio, tower will give you an altitude at which to intercept the glidepath, usually it varies between 3000 and 4500 or so.
With your ten miles distance, you can safely fly and still intercept from below at altitudes of 3000!
Do a Google Picture Search for "Approach Charts Chicago".