1. No, has to come out of wages.
2. Open a taxable account. All the same funds available.
3. Same as 2 a taxable account.
Now, its called a taxable account for a reason--you pay taxes on it--often annually even if you don't take any money out. That's not a bad thing, just how the game is set up. I suggest you read up on the tax implications of owning mutual funds.
Also, since you will be starting mid-year in your 401k make sure you calculate it correctly to hit the max this year (19,500). Then in January readjust your contribution since in 2022 you will have 12 months to contribute instead of 6.