Your listed examples are not correct. "It will come" is correct. "When it comes" is correct. "This game will quickly come to an end." = This game will quickly be done/finished. "When it comes to cooking, my mom is the best!" = When talking about cooking, my mom is the best. Without more context, I'm not really sure how to answer this question.

you can't say neither of that, 'it will come' is correct, after will is used infinitive of the verb and wills doesn't exist just will, it is Future Tense so you don't add s for the third person singular because it's not Simple Present Tense