The only problem I have ever had while splinting a calf's leg is having the splint rub against the calf, creating a sore spot. I used a piece of PVC pipe with old rags stuffed between the pipe and the calf's leg. I have always taken the splint completely off about every week after the first two weeks to see if there are any spots where the splint is rubbing, per the advice of my vet.
As to your calf's foot problem, it is close to where the break is? It sounds like the calf's leg has an infection, and will require antibiotic. It almost sounds like foot rot. I'd call your vet and tell him what it looks like. He may want to look at it, or he may just give you an antibiotic.
I have had to splint two calves' legs the last 4 years, and each one limped for a day or two after the splint was off. Kind of like a human that breaks their leg. I broke mine in high school, and my leg was very sore for a few days after the cast was off. Mainly just from not having all of my weight on it.