For the first part of your question you need to understand the parts of an ILS. ILS stands for Instrument Landing System.
The ILS system may be divided functionally into three parts:
(a) Guidance information: localizer, glide slope;
(b) Range information: marker beacon, DME; and
(c) Visual information: approach lights, touchdown and centerline lights, runway lights
The localizer provides horizontal guidance. The glide slope provides vertical guidance, and the DME and marker beacons provide distance guidance. Notice the straight-in minimums on the ILS RWY 8L approach chart. They are 213-½ which means that an aircraft can fly down the glideslope until it is 200' above the ground. If they see the the approach light system (which in this case is a MALSR) they can proceed another 100'. If they don’t see the runway at 100' above the runway then they need to fly a missed approach.
There is actually a list of things they need to see in order to continue the approach—runway end identifier lights (REIL, the flashing strobes on either side of the threshold)
the runway (itself, the markings, or lights)
the threshold (itself, the markings, or lights)
visual glideslopes (VASI, PAPI, etc.)
the touchdown zone (itself, the markings, or lights)
The localizer approach uses the same horizontal guidance as the ILS but it does not provide vertical guidance. Notice that the straight-in minimums are 460'. That’s because the pilot is relying solely on the altimeter for vertical guidance and it is not as accurate as the glide slope.
Both approaches use the outer marker. The ILS uses it as a way to verify that the aircraft is at 1994' when it crosses the marker. The Localizer approach uses it as a step-down fix—the aircraft can begin its final descent to landing. In this approach the pilot must not descend below 2000' unless the items above are seen. At 0 DME they begin the missed approach.
Most aircraft that are equipped with IFR instruments will have a glideslope. However, it may be inoperative or the glideslope at the airport may be inoperative in which case they would fly the localizer approach.
I don’t know if they do it at this airport, but often airports with two parallel runways will use the localizer approach to one runway with a side-step to the other. If ceilings are high enough, they may do it here.