It's used as a modal particle here, indicating FUTURE certainty (so with or without it doesnt make a big difference to the meaning, better with it though). Also you find this usage in "明天又是星期六了。“ or ”要过新年了，人们很高兴。“

When they mean "happy/delightful/pleased",no big difference. Following are differences off the top of my head ;P : “愉快”is a bit more formal 1.can be used to describe a thing, eg "愉快的旅行" 2.as a wish:"周末愉快！""合作愉快" “快乐”is both a none, an adjective, and a verb. eg1"你快乐吗？”(as a verb) 2.as a wish “生日快乐”"圣诞快乐""节日快乐" In other contexts they can supplant each other i think.....feel free to ask futher questions

他说还是晚上去吧。

“你做什么工作？” 做 can be followed by lots of things like "做功课、做记号、做家务、做作业、做事情, really similar to DO 作 as a verb, it seems to me the most important one is "作为”=AS also u can say 作报告、作测试、作比较、作补充 etc. but i think if u use "做" instead, it still strike people as right

There's no big difference in ur context. But 近来 is more formal, kind of a literal word I think，but used to ask daily things. Eg. 近来可好？ Also 最近 can be followed by a period of time but 近来 cannot. Like u can say"最近几天我很难过 and u can't say "近来几天

A without doubt;)

Am not Is not/ are not Have not/ has not (According to Oxford dictionary)