Any reputable brand will do. I got mine done at my local Ford dealer, using genuine Motorcraft full synthetic gear oil front and rear, and Mercon V in the transfer case ('07 ST).
If you have the facilities to easily gain access to the covers, it never hurts to pull the covers off, wipe away any extra grime and do a visual inspection. If you're fastidious, go for it, but it's not mandatory. OTOH, after maybe 100k miles I'd want to take a peek...