How was the process before

I could find this on the process from theconversation.com:

For decades, UAW leaders were chosen through an indirect process common to many unions. Delegates to the UAW convention chose top officers, and regional conventions picked regional directors.

Has UAW been a sleeping giant this whole time on account of its leadership selection process?

I'm not sure how this affects overall union operations, but it appears there was a lot of corruption involved in UAW leadership that lead to this new voting process. Wikipedia has a summary on these events:

A corruption probe by the Justice Department against UAW and 3 Fiat Chrysler executives was conducted during 2020 regarding several charges such as racketeering, embezzlement, and tax evasion. It resulted in convictions of 12 union officials and 3 Fiat Chrysler executives, including two former Union Presidents, UAW paying back over $15 million in improper chargebacks to worker training centers, payment of $1.5 million to the IRS to settle tax issues, commitment to independent oversight for six years, and a referendum that reformed the election mode for leadership. The "One Member One Vote" referendum vote in 2022 determined that UAW members could directly elect the members of the UAW International Executive Board (IEB), the highest ruling body of the UAW.

Are stand up strikes common? Do they win concessions?

I can not answer to the commonality or how successful these "stand up" strikes are. Overall, striking in any capacity is a tool at the union's disposal when contract negotiations reach a disagreement. How effective this will be is yet to be seen.