Oh, sorry ... the answer to #1 was my opinion about the solution and wasn't actually the answer to your question.

Doug's headers have the reputation of fitting the best. Hedman 4-tube headers are probably the least expensive that will fit with the fewest issues about clearance.

Hookers appear to have the most problems. (Pun intended)

For a mild build, keep the primary diameter relatively small - like 1-5/8 to 1-3/4 - if you don't go for the R.A.R.E. reproduction long branch manifolds.