Unity Cup questions

Is it better to save my spirit bursts for when I also have friend training on a specific stat? In other words, do they amplify each other?

Should I focus more on building bonds or building spirit bursts in the beginning?

How much should I be prioritizing optional/extra races in Unity Cup? And which ones? I had always heard to exclusively run G1 races in URA Finale for skill points, but I don’t know how that applies here.

What ratio of support cards would you use? In terms of speed, wit, power, pal, etc.

Thanks so much in advance!