Let me see if I can help out.
So, the great gift (and curse) of the Harrier is that there are literally infinite ways of landing it, some more useful than others, some more challenging. I'll try not to run on though it's a subject that we could discuss for hours.
Despite what I just said about infinite possibilities, you can probably group the Harrier's takeoff and landing options into the following groups:
- Conventional Takeoff/landing (CTO/CL):
"Conventional" belongs in quotes here, because CTOs and CLs aren't really conventional in the conventional sense of the word. What makes these operations unconventional is the approach speed of the jet coupled with the unusual gear configuration. This is driven by the fact that AUTO flaps are selected when conducting a CTO/CL. Why was never completely explained to us. But the common wisdom is that in the case of an abort or in any case on landing, the nozzles are rotated forward to the Braking Stop (98 deg) to provide reverse thrust.
98 degrees is obviously mostly down and a little forward. So mostly down and the sudden introduction of 62 deg of flaps (STOL flaps with nozzles greater than 50 and also 15 deg of aileron droop) will (and did) get you suddenly airborne, decelerating rapidly with all the bad things that usually come from that. Approach speeds were in the vicinity of 150kts or more IIRC (estimated...it's been a long time), which is fast for a little outrigger geared airplane.
CTOs/CLs were practiced but never anyone's first choice and needed lots of runway.
- Short Takeoff/Slow Landing (STO/SL):
Everybody's meat and potatoes ops and the real "conventional" takeoff/landing. Also infinitely flexible. In short, STOL flaps and 10 deg of nozzles until Nozzle Rotation Airspeed (NRAS), then 55 or 60 nozzles depending on the numbers. TO and Landing speeds roughly between 80-120kts(ish...trying to be generic here).
[Edit: Forgot one!]
You can also do the informal "Rolling STO" (think that was the name) when heavy but you don't want to do a CTO. A rolling STO is simply a CTO where, at a goodly speed, you slowly feed in a few degrees of nozzle at a time. When the plane is ready to fly, it will lift off. And more quickly than with a CTO. This is a generally preferred method of taking off heavy as you don't really want to yank in the nozzles (in the case of a no kidding STO) as you will sit there wallowing in ground effect with all sorts of bombs hanging from your wings.
Works pretty good and more comfortable than either of the other choices when heavy.
As far as landings two varieties and two specialties (advanced):
a. Fixed Nozzle Slow Landing (FNSL): Very low stress. Nozzles at 40-60 on downwind (we learned 50 then 60 at the 90 position [i.e. base leg]), AOA 10-12 units, witch's hat on the horizon (inverted V depressed attitude symbol), power to adjust rate of descent, with a 200-400FPM rate of descent on touchdown. Power Nozzle Braking (PNB) as necessary.
Easy, peasy, lemon squeezy.
b. Variable Nozzle Slow Landing (VNSL):
Also known as a "Wiggly Nozzle", you use this if you need to keep your engine at a constant RPM (oil loss and such) or if you need to do the slowest slow landing you can.
Now, power to 80-100%, then adjust the NOZZLES to maintain AOA and stick to adjust flightpath. Leave the throttle alone!
A little wacky, but it works.
c. Hover Stop (or Braking Stop) Slow Landing (HSSL/BSSL):
If there is a landing you can screw away, this is it IMO. Flown like a FNSL, but at the last (and veeeeeery carefully timed) second, you pull in either Hover Stop or Braking Stop. The deceleration rate is (only half jokingly) reminiscent of a train wreck as you are either getting no forward thrust or actual reverse thrust.
Hope you timed it right to not run out of airspeed before the runway. Now notionally this is no different than what you do when you are doing a vertical landing (VL). What makes these interesting is that you would probably only do this when you were too heavy for a VL but needed to minimize your landing roll. So, functionally you CAN'T VL and will "run out of airspeed" like any other airplane if you don't do it right.
- Rolling Vertical Takeoff/Landing (RTO/RVL):
RVTOs are good for very short takeoff work when you are a bit heavy for a Vertical Takeoff (VTO) and also great for unprepared surfaces (NOTE: any surface that isn't at least reinforced concrete or steel matting is unprepared INCLUDING runways. Harriers earned a special mention in the Davis Monthan AFB portion of the IFR Supplement after peeling back a few hundred square feet of the arrival end of their runway...generally known as "Harrier Footprints". )
Even 10 knots should keep you from having an asphalt party.
RVTOs begin like a STO, except the STO stop is set for 70 deg. Run up the power and when the RPM passes 100%, pull in the nozzles. Do a sort of Vertical Takeoff/STO accelerating transition. Takes about 100ft.
RVLs are a hybrid FNSL and VL. 40-60 nozzles. Actually, we used to do these up to 70 nozzles and a 6 deg glideslope (velocity vector flashing off the bottom of the HUD), but there were too many accidents. Now they do these at 40-60 Nozzles and 3 deg GS...really kind of a FNSL by any other name now. NATOPS gives you the provision of targeting a groundspeed. The big benny here is that even 50kts of speed on touchdown, gives you 2300lbs more carrying weight than a VL in the same conditions.
If you have an expeditionary airstrip, this will be a very popular landing for you.
- Vertical Takeoff/Landing (VTO/VL):
Everyone's favorite and no need to describe it as everyone already knows what it is.
I guess you could argue that the VTO/VL is more risky than the other landings, but it is what the Harrier is built for and no Harrier pilot would think twice about doing one. VTOs/VLs aren't dangerous or difficult per se. You just need to respect the limitations of the airplane and she flies in a very lovely fashion.
The plane is a little unstable, but it's not like walking through a room full of banana peels either. You can't eat a sandwich while doing one, but I think that is true of any airplane. Obviously, the smaller the power margin you have, the more careful you need to be. Don't try sweeping into the pad like a Huey on a hot, high, or heavy day or you are going to run out of throttle which is a terrible experience mostly because you're not only going to crash, you're going to crash very slowly.
VLs are used a lot when they can be considering the conditions partly because hey, Harrier; but also because you are probably light anyway and a pad and a short runway effectively becomes what for conventional aircraft would be a two runway operation, one for taking off and one for landing.
As for the higher fuel burn used during VLs, it's really no more than you would use for a take off or go around. Performance limitation and available runway are really the deciding factors in which landing you choose to do. Aside from that, there is no wrong method and pilots will generally try to mix them up to keep in practice.
Well, so much for keeping it short once again. But hopefully that answered some questions.