Regarding some of your questions.... I am not 100% sure, but in the 2007 version, InfoPath was an enterprise function. So the use of InfoPath may be a function of the version you have (Foundation vs 2010 Enterprise).
SPD may be a good start for you, especially since you can now export your SPD developed workflows and import them into VS 2010 to update the functionality.
Regarding the board editing... Based on your security implementation (FBA vs AD) you probably want to do some kind of role check on the load of the edit form. I would probably start by having a ASPX form (not Infopath) that you can determine the type of user you have. Based on the user, you can display or not display appropriate fields and fire up event handlers to buttons as need be.
I would most likely start with a sequential workflow since you do not have numerous steps that need to be worried about. State Workflows are for more complex implementations.