I just went through this not long ago. I'll do my best to save you some research and make this as easy as possible.
To answer your first question, yes thats definitely a CV failing. Bad yet? no. you'll know for sure when its completely destroyed (you'll be embarassed to drive with it its so loud). The stock CV's on these trucks are terrible. The boots themselves have very little give to them, so it puts a lot of strain on the metal bands. If you see grease coming out, that means they arent sealed. If they arent sealed, dirt/debris will get it and destroy the joint, which is what has happened to yours. So now that we know it will need replaced, lets get on to the other questions.
Yes, you can do it yourself. I did mine with basic hand tools. You dont need an air ratchet as long as they arent really seized on there. If they are, spray some PB blaster on there. You have an 07 so i doubt they're on their that bad. There are only 2 areas you might have a problem with. 1) the axle nut size. Its freaking huge. i dont remember the size, but its something like 24mm. 2) actually pulling out the CV from the front diff. If you have a slide hammer at your disposal that would be nice. otherwise, figure out a way to get the same effect on it. While im writing a novel, i'll do a writeup
1.) lift vehicle and allow front wheel to hang
2.) remove wheel/tire
3.) remove caliper (4 nuts in total) and slide rotor off
4.) remove axle nut
5.) remove nut from the tie-rod (no puller necessary)
6.) remove nut from the top of the spindle connecting to the upper control arm
7.) LIGHTLY tap the top of threads in a downward motion to pop loose the spindle from the Upper control arm. No puller is necessary here either
8.) Rotate spindle down and out of the way
9.) using a slide hammer or your creative juices, somehow pull the halfshaft out of the front differential. Dont worry about tearing it up, cause its garbage anyway. WARNING: be very careful to pull it straight out and not twist it around all over the place. You could damage the retaining clip on the inside of the diff (if you damage it you'll be opening up the diff... not good news)
10. Once the half shaft is out, you're half way home. Take your new one and slide it into the diff until it clicks into place. Make sure its seated but trying to pull it out. If it doesnt come out, its seated properly.
11. Reinstall everything in reverse.
As for where to get the new CV. I highly suggest not getting an oem one or you'll have the same problem you've got now in the not too distant future. I purchased mine on ebay beleive it or not. Something like cvman was the dudes user name. I cant tell you how impressed i am with the product. The boots have a lot more give in them and they're a little more flexible than oem. The price aint bad either -- less than oem from the dealer. WAY cheaper than a name brand like moog, kore, etc. and the quality you need.
If you have any questions, feel free to ask, as like i said I just went through this so its all still fresh.
