IRAs - Traditional

The required beginning date for distributions is usually April 1st of the year following the year you turned 70 1/2.

No. You cannot contribute to a traditional IRA once you reach 70 1/2. The year in which you turn 70 1/2 is the tax year you cannot contribute to an IRA. For example if you turn 70 1/2 in the current year, you can still make a contribution by April 15, of the following year for the current year but cannot make any contributions for a traditional IRA related to the following tax year.

You must make your contribution by the filing due date of the return (usually April 15), or the date you file the return, whichever is earlier. An extension to file your return does not extend your time to contribute to your IRA.

IRA and pension deductions are based on earnings.
Earnings are subject to payroll taxes, specifically social security, also referred to as self-employment tax for sole proprietors.
If you are not paying payroll taxes on your trading profits, you are not eligible for an IRA deduction or pension plan.
However, you may qualify for a spousal IRA if you income falls within certain limits.

Contributions to IRAs must be made by cash. Checks and wired funds are considered to be cash.
You may be eligible to borrow the money from the brokerage house against your stock. This is called margin.
In this way you do not have to sell the stock and you can still fund your IRA.