Regarding the programming of training one must always keep in mind there are specific abilities which require a great deal of adaptive energy, and to increase other abilities the training of such abilites must be decreased. Specifically speaking to your situation, to improve such qualities as speed-strength and speed, a large volume of technical training will only interfere with possibile gains of these abilites. I'm not an expert by any stretch of the imagination, but when thinking of karate I already see abilities such as speed-strength and speed of movement being trained with the dominant training modality being that of speed of movement. This begs the question, "is additional training of this sort needed?" You must always be mindful the actual sport played trains the most specific of abilities needed for sporting succes, and this is not to say additional training elements are not needed beyond. In your situation, while not knowing anything about you (strength measurements, sporting abilities, injury history, training yrs, ecetera), maximum strength training would provide a solid base for improved performances as most who are in the general age range of yourself lack such abilities and improvements of this specific ability generally improve subsequent performances. Not to mention the biological age you are at genetically predisposes you to "easy" gains by the use of general means.
For the development of "explosive endurance", correctly stated as alactic capacity, I highly suggest the reading of the following article http://www.8weeksout.com/articles/31-sac/57-secrets-of-muscular-endurance. For your benefit I would also read the remaining articles on this site to help you better understand the bioenergetic systems of the body, which all sport training should be based. Hope this points you in direction you seek.
Joe Grachen, USA