Microtransactions aren't present in franchise mode so unless you plan on playing MUT, they won't ruin or even have any impact at all.
The vast majority of dealing with player management comes in the offseason but there are player negotiations that occur week-to-week throughout the season starting in week three. Also starting in week 3 is player scouting which is the other major player management task that you'll face and both of those and pretty much every activity can be set to Auto giving you the ability to control what you want to deal with and what you want the CPU to handle. Franchise mode is definitely built around your playstyle of going week-to-week and just focusing on the games. Pretty much everything has tips and directions the first time you do it so even being away for a long time, you should be able to pick up things pretty fast.