I'd like to replace the stock single disk HU with like a kenwood HU. is that possible? If so how would I do it? Please give me all the tips, facts, and information I need to replace the HU of a 2010x.

there are several threads on this, you can use the search function for more details, but here is a rough idea:
1. Metra Dash Kit
2. Antenna Adapter
3. Wire Harness
4. Headunit (of course)

You can get the part numbers by going to crutchfield.com and when you insert the vehicle information you can say 2008 Nissan Frontier, 6 speakers, King Cab, Non-Rockford Fosgate system, and factory system.
(the reason for this is that Crutchfield likely has not gotten around to test fitting the X with equipment, but the frontier is the same setup)

that should let you pick a head unit which will then auto-populate your cart with the needed accessories (you'll want the black Metra Dash kit, i heard the grey is pretty bad)

You can then use this information to search the internets for the parts, or you can buy from crutchfield and take advantage of their support.

do you know where i can see a DIY instructions of removing the stock HU from a 2010X? or does crutchfield.com come with the set of instructions to removing the HU?

it's easy peazy, 4 screws pull out the hu, remove the hu brackets, unlpug from the hu. be sure that if you have a double-din deck you have a mount kit because the original hu is much wider. wire-up the adapter to the new deck first before installing, attach mount kit and antenna adapter, and reinstall. if you can work a screwdriver and strippers you're all good. that's the short version

yeah, crutchfield should include info. here's the quick and dirty:
1- remove the little square tray in the center of the upper dash- use something soft (plastic picnic spoon) or be careful with a flathead screwdriver as the plastic is soft and may scratch). it removes from the sides, NOT the front or back. just pry it up and it'll pop off.

2- there is a philips head screw in the center of the console that you can now see, it holds the center of the entire dash in place. remove it.

3- the entire center (HU, climate controls, and the 2 vents flanking the HU) will now pull out. be careful, all the wires are hooked up, and the shifter is below, watch the plastic-on-plastic contact, again this is soft stuff and may scratch.

4- unplug all connected wires to free up the big chunk of plastic

5- now you have access to the screws holding everything on

6- the HU isn't hard to remove, but you will need to remove the climate controls so they can be inserted into the new Metra dash kit.

7-from here, i think the metra kit has all the info you need.

im a noob and im assuming that this is the metra dash kit http://www.crutchfield.com/p_120997581/Nissan-In-dash-Receiver-Kit.html?tp=3121 ?