Yo, congratulations on the new Rig, I'd love to see some pics. As for the oil the manual states you can use the following oil weights:
0w20
5w20
5w30
10w30
As for oil brand any off the shelf synthetic will serve you well in these engines. I personally run a 0w30 or a 5w30 with great results; switch to a 30 weight oil on my second oil change and immediately noticed a difference. Oil change interval is really a comfort level with you personally, I change my oil every 5k. I know the oil I use can easily to 10k+ but I enjoy the peace of mind changing it at 5k. And it gives me an opportunity to give the under carriage a good visual inspection. FYI wile your under the rig remember to grease the driveshaft.
Lots of youtube videos showing the oil change and driveshaft procedure.