This is actually an established historical fact about what the term "disciple" meant. It's not something from the Bible because this was a cultural concept of the Jews. Go look up the significance of "Come follow me" in Hebrew. It's a lot more than just believing a rabbi's school of thought.
The New Testament doesn't teach to help the elderly cross the road either, but we are to do it out of love. Application of love, that's why. Furthermore, how can it not be out of love? The Sabbath was meant to be a blessing, but you make it out to be a burden. It's only a burden if you see it like the Pharisees - a day of not doing some things. Whereas if you see it like Jesus did - a day to do good and enjoy good, then it becomes a refreshing day.
He taught proper Sabbath observance to the Pharisees - He let them know it was lawful to do good on the Sabbath and relieve suffering.
It's the historical definition of the word.
That depends on how you define it. I don't observe the sacrificial system because Hebrews clearly states Jesus became High Priest and sacrifice. I don't observe the Feast of Unleavened Bread per se, but I observe the Communion which is what the Passover was about... I'm not going to list all here, but if you so desire to go through each one here, then ok. But, a few of the laws definitely can't be kept now that Jesus is High Priest in heaven, like men's [bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse] laws and women's menses laws, since there's only the heavenly temple now. If you can find a modern day application, let me know. There are laws about slaves (indentured servants, not the same as Roman, English and American slaves) that I don't follow because I have no slaves. I'm vegetarian, but I believe in the clean/unclean laws being given for good reason.
You got a checklist? Btw, Jesus did not keep the agricultural laws because they did not apply to carpentry. The laws were about context as well. "If you have crops", "If you have slaves", "If you have sex", "If you have children", etc.
Actually, it was already established post-Moses' time among the Israelites that tithe in money was ok. The point was tithing your financial gains.
Hebrews says our High Priest is Jesus, so we tithe to the storehouse of His work (which was the purpose of the tithe - to support the ministry of the priests), so it becomes the ministers' salaries.