when selling then buying how do you execute? Sell first then buy new position or keep cash on hand?

That's where having an account at M1.com makes your life easy. You just have to get your head around their weird terminology.

Go to "research", edit your "pie", remove the ones to drop and add the new ones.
Save the edited pie, check "select all" and check "equal weight".

Go back to your portfolio (under Invest) and look at the "Upcoming Activity" to verify. Do *not* click "Rebalance" here.

The next trade window, it automatically does all the sells and buys the underweight ones with the cash. It will do a full buy of the new ones and if there is any money left over it will buy more of the most underweight ones.

At a normal broker, yes, you sell everything that dropped off and with that money buy equal dollar amounts of the new stocks. You have to do the calculations yourself. These days many brokers let you specify a dollar amount for the quantity. FIDO, Schwab. But not Etrade or Vanguard or Merrill.

I've used M1 for several years. It's very easy there. Doing it at Fidelity and Etrade is a P.I.T.A.