We have a upcoming project in A286 iron base superalloy HRC 32 flat stock
(30) .276" holes drilled 1.25" deep at a 50 deg angle to cross holes
and
(42) .197" holes drilled 1.05 deep at a 60deg angle to cross holes

Should I pre drill with a short drill first or go in with an endmill and make a flat

Also we are considering drilling deep holes in this part
(2) .313dia 17.23 deep
(4) .375dia 17.3 deep

Any advice on sfm and chipload on carbide drills would be appreciated, along with any other things to look out for.