You asked about payment. A rule of thumb for estimating wages is the Social Schedule of the U S census. A schedule exists for every county, and they contain much valuable information. The typical wage for common day labor is given as ten cents. Quarter a day seems reasonable for skilled labor.
http://www.ancestry.com/wiki/index.php?title=Non-Population_Schedules_and_Special_Censuses#Social_Statistics.2C_1850.E2.80.931880

Except in mounted commands, I've not seen blacksmiths assigned to a regiment. After 1861-62, you'd normally find teamsters and other men involved in transportation assigned to brigade, division and corps wagon trains. Blacksmiths, wheelwrights and carpenters were probably detailed to wagon trains. As mentioned in times past, we would also expect to find Black Confederates employed in COnfederate military transportation service.

If you find an account of Confederate transportation, I'm interested.