2010-2012 runners can be had for good deals since they are mildly used at this point and they were pre-refresh (basically Toyota put a few new body pieces on 2013+ models, other than that everything is pretty much the same).
There were some TSB's to be aware of for those years of 4runner. The NHTSA used to have them listed on their website, but they don't seem to list that info anymore. Some of the more important ones had to do with the a driveline clunk. There are also air bag recalls for most Toyota models, including the 4runner. Takata is the airbag manufacturer and Toyota seems to be doing a gradual recall process, which is phased in depending on the year of the vehicle and its location (those in humid, wet climates, seem to have a higher priority). Honestly, except for the airbag recalls, I havne't been too worried about any the TSB's. I've driven my 4runner for over 30k miles now, and I haven't noticed any issues or breakdowns. The TSB's might be limited to just a few of the 4runners, but it doesn't hurt to talk to a dealer about any that are relevant to your specific vehicle.
If you're planning to go offroad, get the Trail edition. It's as simple as that. The main difference relative to the SR5 is that is has the rear locker and a manual transfer case shifter (as opposed to the SR5's electronic dial); the KDSS is an option on the Trail, but IMHO it is not necessary, and in fact it may be more of a hindrance than a bonus if you plan on adding aftermarket suspension. The newer models come with optional leather seats and heated seats; I'm not sure if they are available on the older models, but I'd look into that since the stock seats, while not uncomfortable, aren't the best in the world.
As the owner of a 2011 trail, I'm pretty happy with the vehicle. I've driven this thing through a lot of challenging terrain and roads with minimal drama (that rear locker has been a huge help) and stock ride height and departure/approach angles, while not amazing, have been adequate for most of the areas I've gone into. The stock suspension is kind of floaty on the road, but that works to your advantage when you get offroad, especially when you air down the tires. The engine/transmission combo is deadnuts reliable and has performed flawlessly (even in sub zero temperatures) with basic maintenance, though it's power delivery and fuel economy is nothing special. The old-school manual transfer case shifter is a nice touch too.
Get the Trail, drive it, have fun....you may end up finding that it needs little to no modification for your purposes. But if it does need modification, there is a huge aftermarket for it.
