Power Bobtach allows you to connect and disconnect front mounted accessories without leaving the cab. Without the power Bobtach, you have to manually lift two levers on the Bobtach plate to release an attachment, then hop back in to set down that attachment, drive over to pick up the next attachment, and again hop out of the cab to lower the two levers to secure the new attachment. Just a convenience item, depends on how lazy you are, and how often you switch attachments. If your attachments also connect to the aux. hydraulics, you will still have to get out of the cab to connect / disconnect those hoses.
Floorboard riser is some sort of spacer to rest on the floor, if your legs are too short to have your feet reach the floor while seated. I'm 5'9", and don't have any desire for a floorboard riser. I have a helper who is 5'4", and she can touch the floor just fine. I do have the optional suspension seat which sits a little higher than the standard seat. Not sure how short you have to be to need this item, personal preference would play a part also.
Remote rear hydraulics give additional outlets for the already existing Aux hydraulics mounted on the front boom. I don't have this option, but I understand it is controlled with same joystick switches. Maybe someone who has this option already can confirm? Rear hydraulics would be used for an accessory which you can tow but requires hydraulic power, like a rear mower or hydraulic powered salt spreader.