It does poorly so they kick it out. So, then the DOW is not an index, but a club.
For the DOW to have some meaning it should include all companies’ stocks, not just 30.
No, just go back to the original members and calculate forward from there. Don't forget to give full current value for US Leather Company.
For companies that have been bought or merged, give full value for their stock at the time they ceased to exist.
There are many index funds to choose from. The Dow 30 is the smallest broad-based index fund. If you want the broadest broad-based index fund, go with the Wilshire 5000. Why should the Dow change?