Look out at
http://yrarg.cncguild.net in Tuorials section, something can help you out.
As for making new infantry in a 3D program....Very little people actually make them NEW...you can get good results with cut and paste. Try 3DS or GMAX if you wanna adventure yourself, but honestly...i do not recommend unless you wanna later dedicate to 3D graphics.
As for the Infantry sequences...ill build up a tutorial on them later today, hang on for a couple of hours