Boiler Header Size and Other Questions

I will be installing a Slant Fin 60,000 Btu input boiler with a Cross four zone manifold. The heat loss for the structure is @ 47,500 Btu's and the four zones of fin tube are plumbed using 3/4" copper pipe. I plan on using a Alpha 2 pump with a magnetic air and dirt separator. My question is would you use 3/4" copper pipe out of the boiler to the manifold, or 1" diameter pipe. The 3/4" pipe would be cheaper for my customer and would still be under the 4 feet per second rule for the air separator, but I don't know if it would be too much a restriction for the 1" diameter Cross manifold.

For my next question, how is every one liking the Cross manifolds since they are still new to the hydronic industry?

Finally, on the Slant Fin Sentry boiler line the circulator appears to be bolted to the return side of the block and not using a NPT. tapped hole from the factory. I would be ditching the factory circulator and mounting the Alpha 2 and expansion tank on the outlet side of the boiler pumping away from the PONPC. Can anybody confirm there is a 1-1/2 NPT. on the return side of the Sentry boiler along with the four bolt holes, or will I need to make some sort of adapter to hook up my return pipe.

Thanks,
Noel