and have to brake so hard ..
I think I definitely qualify as an olde phart past his use by date ... I can only recall really significant braking during really significant need occasions.
On the routine longish runway it was a matter of pride to delay the brakes (in dry conditions) until just a touch might be needed for the turnoff .. reverse was in and high as soon as the interlocks permitted one to pull the levers back further.
It seems the only way to bleed off aircraft speed is to reduce the thrust
The intention is not so much that the pilot actively sets out to reduce the speed. Rather, if a stable approach is conducted, then, in the latter stages (say, the last 200 feet or so), one probably should notice a modest and progressive reduction as the aircraft transitions the boundary layer. If one rigorously is pushing and pulling the throttles to stay on speed then this shear-related bleed, of course, will be hidden. This is more so the case in gusty conditions. In nicely smooth conditions, where one can maintain a sensibly constant thrust, the effect should be more readily observed.
The speed reduction is the idealised situation and we do the best we can in the particular circumstances. Main aim is to nail the flare and the touchdown point to avoid floating off down along the runway - that is the real hazard facing the pilot.
(i.e. reduce the thrust: for example from approach idle to flight idle) during the flare
... and, if you don't do that routinely, sooner or later you are going to be bitten rather badly on a short runway. Fine to enter the flare with thrust on but it needs to be reduced to closed throttles during the flare transition. It doesn't take too much residual thrust on to see the float take over ..
you will loss altitude in case of Go-around because of low acceleration/spool up time
a missed approach from flare/touchdown is an extremely unusual situation. In general, and especially on a short runway, when the throttles are closed you are either on, or nearly on, the ground.
There is a risk of collision with the ground.
A missed approach from the flare would be expected to result in a brief touchdown and is not uncommon in the case of low vis operations. There ought to be little risk in such an event. Certainly more a case of interest in older aircraft with slow spool up but still it should not be a significant risk other than in the case of a fairly short runway.
I think there is conflict between bleeding off wind additives (reducing thrust) and performing Go-around.
a) What do you think?
of course there is. However, one sets out to balance the risks. If you don't carry some additional speed the approach risk increases and if you do the roll out risk increases. With the ample factors on scheduled landing distance the risk is small PROVIDED that the pilot nails the flare and touchdown.
b) Is it easier (efficient) to bleed off wind additives in prop aircraft?
indeed - propellers have much the same effect as speedbrakes. One's first landing with a feathered outboard engine is illustrative during the flare as the remaining throttles are closed, especially with larger HP engines.
c) Is it possible to bleed off wind additives in jet aircraft using thrust reversers during the flare or before the flare?
generally this would be a guaranteed outcome .. along with a significant probability of breaking the aircraft on touchdown.
(Assuming it is possible to use thrust reversers in flight as allowed in few aircraft).
... but not during late final approach I shouldn't imagine ?