On the seams, I would put masking tape on each side of the joint and fill it with walnut wood putty. Before the putty is dry I would remove the tape. Often if you let the putty dry and then pull the tape off it takes the putty off too. Then sand flush with the finish and touch up the finish. For the rough edges, it looks like a phenolic veneer (Formica backed). If that is what it is you can use a mill bastard file and just file it smooth like you would a formica counter top. If it's all wood you could just sand it smooth and touch up the finish.