Alright.
Kenjutsu is as you said, the way of the sword which emphasizes using a sword as an extension of your body. Kenjutsu itself falls under the broad and general way of Bukijutsu, or weapon techniques. Kenjutsu is used by both samurai, as well as shinobi, although samurai use it more, and it is the basis of their fighting style. You use a sword, as a medium for techniques meant to cut the opponent, or do damage that involves slashing. Most people choose a two handed approach to using a katana, due to the fact that they can get a lot more speed and power out of their attacks, since they are using two hands. Others choose to dual wield katana, or even triple wield (shoutout to Caliburn) their katana. Some people on the other hand, use sword techniques with a single hand to attack the opponent, while using their other hand to launch other attacks. It really depends on your own preference.
Chakra Flow, is the process of using elemental and regular chakra to increase the potency and potential of a blade or other weapon. For example, Kirabi coated a pencil with lightning chakra, and it would have potentially killed Kisame, if he hadn't avoided it. Effects of chakra flow vary from element to element. For example wind and lightning increase cutting power, while fire causes burning damage, and can cauterize wounds. Chakra flow is used extensively in kenjutsu, in order to increase the speed, power, and cutting potential of your blade, and making it more lethal.
Close Quarters combat, is not necessarily limited to close range techniques, or to taijutsu, and kenjutsu. You could use elemental jutsu in short range, although you might injure yourself. Close Quarters combat tends to have a high risk, high reward, type atmosphere. In a lot of cases, you can end a battle with a single blow, especially if using a weapon. Although, the reverse is also true for the opponent. It really depends on your own preferences, some people gain a large arsenal of close range weapons, CFS, and jutsu, and fight exclusively in close range. Now, a lot of jutsu in the taijutsu and kenjutsu list can be done with freeform, that is not using a jutsu and describing what you do in words of your own, so if you don't want to waste a jutsu slot, it might be a good ide a to use them instead of an actual technique. In addition, you can dodge a lot of kenjutsu/taijutsu freeform without using a jutsu, but not all.
Any questions?