In my experience, installing suspension alone is a far easier task than installing the ARB bumper. Maybe it's because I have a lot of past experience with the suspension, but more likely that it's because the ARB involves drilling, painting, splicing wiring, disassembly of the stock bumper, modifying transmission cooler lines, and so on. Plus you'll be installing and wiring a winch.
Best advice I have is to give yourself at least half a day to do the bumper, unless you have a good helper to work on one side while you do the other.
Use a piece of cardboard or blanket on the ground to prevent your ARB from getting scratched up while you're manipulating it on the ground. Same goes for your OEM bumper - I sold mine for $100, after removing the fog lights and selling those seperately for good money too.
Are you going to install fog lights in the bumper?
As for the OMEs, there are several good write-ups on installing those available here and on the toyota120 site. Be careful of brake lines, ABS wires, ball joint boots. Hopefully you bought your OMEs pre-assembled. Otherwise you probably want to get the coils and shocks assembled by a shop rather than using a handheld compressor. Read the write-ups many times and make sure you have all the tools before you try to tackle this project. I highly recommend two pairs of jack stands, with one of which being tall enough to support your truck by the frame several inches above stock height. You also want a ball joint puller that uses the bolt you turn to pop apart the joint - don't use a "pickle fork".
Make sure you know ahead of time where to disconect the X-REAS shocks from the hydraulic system. I did not preserve my X-REAS when I removed it, since one shock was leaking and the rigid hydraulic lines were a bear to remove without bending them. You have the option of leaving the hydraulic system attached to the truck and just removing the shocks, but c'mon, are you really ever going to go back to X-REAS??? Nope.
Now is a good time to install the longer stainless brake lines from Slee OffRoad, since you'll be under there anyway. "Speed Bleeders" are well worth the money any time you have to bleed brakes.
Good luck, have fun, be safe, and let us know if you have any specific questions.