The white face is a dominant gene, I would think you would end up with at least half white face. If I remember my biology one in four will have the white mane and belly of the hereford. Most of all why do you think you are upgrading here. Not knocking Limo's as my neighbor has some dang good ones. But there is some good herefords out there also. My neighbor and I haul our calves to the sale barn together both bring the same price. If you want solid red cattle switch to limo's or gerts.
Son I can't help you here, for the last thirty years I've been trying to make them bigger on less feed. Thats the object when selling by the pound. Maybe one of the members will see your post that knows about minitures.
Well the breeding concepts are the same. If you breed the limo to the hereford cross back to a limo for enough generations you'll get a solid red. The only down side is you'll probably increase your size but that could be fixed eventually.