Welcome to Land Rover Disco ownership,
I can't agree more with the others about maintenance and fluid refreshing on these rigs. The disco is easy to work on and all procedures can be easily learned from the service manual we all know as the "RAVE" manual. It is available all over the internet in PDF form for free. I would suggest getting a copy of it for working on the truck. If the front driveshaft has not been replaced with a unit with all greaseable u-joints, it would be important to replace the driveshaft. Supposedly many Discovery 2s end up in the scrap yard after the non-serviceable u-joints fail and the end of the front driveshaft plows into the transmission and catalytic converter. The catalytic converter is so close, it roasts the factory non-serviceable units until they are dry and when they go, it can be catastrophic. This can be a silent process, so tread cautiously.
Also, the coolant can never be checked frequently enough. I pop the hood every day when driving my D2 to check the coolant reservoir. It may be a little too much to check it that frequently and my significant other makes fun of me for it, but I don't want to roast the engine in the disco. Speaking of that, I will also suggest keeping an eye on the real temperature of the coolant. From what I have read, the gauges only let you know the engine has overheated past the point of no return after the fact. I bought an OBD2 bluetooth interface that communicates with my phone to give the real engine temperature and a lot of other parameters. The interface was a bit over $20 and the app was free, so low price for peace of mind. There are also the ScanGauges for a more permanent solution (may be more thorough, but haven't tried one yet).
I wish you many years of trouble-free Discovery ownership and if you have questions, I am sure a member of the Land Rover community will be able to help you out. As for racks, I am in the search for options myself and hope you find what you want.