Eeek, there's a fair amount to get through! You're right there is so much conflicting advice (even people on here don't always agree with each other). There are some ok care sheets on here so take a look (in the lizard section on care sheets).
Housing - Really there should be one dragon to a 4x2ft viv. Housing a male and female together often ends in disaster (or at least expensive vet bills!). They will inevitably breed, this means unwanted clutches (there's far too many beardies around as it is); a very weak female after laying said clutches and having the male to fight off; possible egg-binding of the female; illness; possible dominance where one will get the best food, heating and hides etc (often results in injuries or a very 'depressed' dragon). I could go on, basically if you get them prepare to separate them! A spare setup never hurts.
Temperatures: Basking spot (directly under the lamp where the beardies bask) 105-115F. You're aiming for them to bask for 5-10 minutes at a time. Warm end (measured against the side wall of the hot end) around 90F and the cold end (measured against the side wall of the cool end) around 75F. Any heat sources should be connected to a thermostat, this will reduce fire risk, reduce overheating and save electricity. Temperatures should be measured by digital thermometers (analogue/dial ones are useless!). Contrary to popular belief, the cold end is as (if not more) important than the basking end - they need to be able to cool down and escape UVB exposure.
Try to provide 'layers' under the basking spot - this will allow them to choose the height and temperature at which they want to bask.
At night all heating can be turned off - they require a cool temperature at night to enable their bodies to relax and switch off. They can cope with cold temperatures easily.
UVB - high percentage (10-12%) UVB tube that's around 3/4 - 2/3 the length of the viv starting from the hot end. There's a great guide on this website > Lighting Guide for all Reptiles from Arcadia
< Arcadia T5's with reflectors are the best around and last a year (unlike other brands that last 3-6 months tops).
Substrate - Up to you. Sand is fine as long as your husbandry is spot on (avoid calci-sand though). Others could be lino, tiles, slate, newspaper etc.
Diet - Gut loaded and dusted live food. Variety is key! Adults should still consume a fair amount of live food, but for veg have a look at this guide > Untitled Document
< you want to choose high calcium, low oxalate foods mostly. But again variation is key.
Supplements - I recommend Repashy calcium + - there are plenty of threads regarding supplements so you can have a search around for that.
Decor - Provide bits of wood for them to climb on and hide under. If you choose to provide a water bowl keep it in the cool end (you want low humidity)
That's all I can think of at the moment but no doubt I've forgotten something! Hope it all makes sense
EDIT - Haha that was a bit of an essay ^ apologies