First the Sharingan doesn't "give" Chakra a color, Chakra has a "color", and the Sharingan, and just about every Doujutsu for that matter, allow the user to "see" it, with the Sharingan taking it a step further and allowing the user to perceive certain qualities within Chakra to allow the user to deduce the Element of a given technique's Chakra. I know that's basically semantics, but it's important to specify in my opinion, especially when talking about Elements. For example if the Chakra is highly energetic, it could be either Lightning or Fire, but if it has vibrational qualities it's the former, while Chakra that appears darker, or more dense would be Earth, and so on.
Next, it's not just techniques that you "know" that you are able to Copy. You wouldn't be "copying" a technique if that were the case. Specifically the Copy Technique allows you to perceive all of the components that make up an opponent's Jutsu, and use it yourself. For example, say I use a Fire Release Custom Jutsu with a single hand seal, and you also have the ability to perform Fire Release with a single seal. Between witnessing the specific seal I use, and the Sharingan's ability to percieve the flow of Chakra, you would be able to recreate that technique on your own, regardless of whether or not I've taught you that Custom. Now say I use it with a single seal, but you only have the faster Handseal specialty. Because you don't know the full string of seals, even though you know the rest, you can't recreate that technique because of the lack of seals. This can be applied to many situations, one of the most interesting I've recently come across being Arthorius copying Mirai's CFSJ during combat. The CFSJ didn't require handseals, and was Genjutsu based so it was almost entirely based on internal Chakra-based actions, which the Sharingan can percieve, allowing Arthorius to effectively steal something he didn't have. As for your question, if it is the first offensive action in a given timeframe, you have to come after them, as your reaction is based on their action(s), but you could definitely witness the technique being formed, and respond with your own fast enough to counter with your own version, though that would be relative to things like distance and how long the technique takes to perform, and stuff like that.
Everything else is correct, and as for Izanami and Izanagi, yes, using them makes you blind. It's not a completely permanent thing that affects your bio forever. In the NW it's for the current arc, and for fights it's for that fight alone. For what you get out of them, it's best to use them when you absolutely need to.
Moving on, given how sparse my replied are, it wouldn't be fair to give you roleplay training for (E)MS activation, so please break the technique down, and we'll move on to the other techniques.
( Doujutsu: Eien no Mangekyou Sharingan ) - Eye Technique: Eternal Kaleidoscope Copy Wheel Eye
Type: Supplementary
Rank: Forbidden
Range: Short-Long
Chakra: 70 ( -20 per turn to keep active )
Damage: N/A
Description: The Eternal Mangekyo Sharingan literally meaning " Eternal Kaleidoscope Copy Wheel Eye", is the final step in the evolutionary state of the Sharingan. While Mangekyo Sharingan is but an imperfect Dojutsu, unable to sustain and keep its own power, weakening with each use, the Eternal Mangekyo Sharingan brings control and balance to the power wielded. By merging the users own MS with that of his sibling, the use is able to awaken the EMS. The EMS grants the user the same abilities granted by MS but to unsurpassed levels. While granting the user the ability to perceive the world with increadible insight, it also grants the user the ability to see through S-Rank visual illusions and track the movement speed of almost anything, perfecting the already amazing abilities of the standard MS, like casting Genjutsu without the need for handseals as long as a line of sight to the target is available. A unique feat however, is that once the user awakens EMS, he loses access to his normal MS, transitioning from 3T form to EMS directly. While MS damages the user as time passes and severely tires and drains the user as its used, the EMS doesn't. The user can keep it active without losing his eyesight or damaging himself and can use the normal MS techniques with no activation reduction or drawbacks. Its true that the chakra cost is higher, but the user will feel little to no effect in his stamina and energy. Through his EMS, Madara gained the ability to control Tailed Beasts by forcefully using his sharingan genjutsu/mind manipulation abilities to take control of the Bijuu and temporarily sever its connection to the host. If the Jinchuriki is in normal form or entering one of the transformations, it's blocked from transforming for 3 turns. If it's in incomplete form, it's forced back into normal form and left unable to access his bijuu for 3 turns and if its in complete form, the user gains control over the bijuu, manipulating its movements/actions completely for 2 turns or until the complete form ends (whatever comes first), leaving the host unable to acess his bijuu for 3 turns.
Note: Only usable by bios with EMS after meeting the necessary requirements.
Note: User needs to have activated his 3T Sharingan beforehand
Note: Once activated, lasts 10 turns per use and once the user has held the ability for 4 months, can be done passively, with no move cost.
Note: Using MS techniques don't reduce the activation time.
Note: To avoid direct Eye Contact and be able to focus only on the body movement below the chin, the opponent needs to have mastered Taijutsu to possess the necessary skill.
Note: Predicting the nature of a technique or what it exactly is requires the user to either know the technique or that its a cannon technique.
Note: While active, as long as a clear line of sight and the range is respected, the user can cast normal non-Doujutsu Genjutsu without the need for handseals. However, Doujutsu illusions still require eye contact (if feasible) or their own requirements; this ability only affects regular Genjutsu.