Is it faster to grab the star in 4-1, or to get a Superball from the bonus game and blast through all the enemies? Also, is it worth it to stay as Superball Mario throughout the first half of 4-2 instead of damage boosting?

In 99/100 cases - if WR does it, you should do it too.

Starman on 4-1 allows to not slowing down in the pirahna plant session which means you can outrun the bullet bill faster, to optimize movement in killing plants with superball in loosing as few frames as possible to begin with is deemed very hard from the explaination I've had.

4-2 Pretty much the same answer..

Now TAS does skip the starman and it makes the use for superball that you are asking for, let me know when you reach TAS level over WR holder and I'll be the first to watch your streams for WR bop SeemsGood

Thanks for the info. I'm nowhere near TAS level, and have only started doing complete runs recently, but there's not that much info available about the nuances of this game so I thought I'd ask.