More filter and hose Q's

[longwolf]

I'm getting ready to move my stock fuel filter and add a separate filter for the rear tank.
I just noticed that the stock filter has a 3rd nipple going out to the return fuel lines, between a couple of the injectors.

Can I just cap those off or are they needed?

Also, I'm planning to use 3/8 inch parker hose for the fuel lines.
But I believe the return lines are 5/16th.
Parker doesn't make a hose that size.
Can I go to a 1/4 inch or maybe use 3/8th there too?

Oh, this is on an 84 6.9L.