Let's say I wanted to take 1.5 grams of protein for every pound of bodyweight, is that for lean mass or total mass? Like if I weighed 300 lbs with 200 lbs of lean body mass, would I take 300 grams of protein a day or 450 grams?
You take as much as you can IMO
I've seen both. It depends on your goals and how you respond to it. The best way that I've read is to start with one based on lean body mass and then increase from there, every two weeks, if you are not seeing desired results. It will take awhile to hit the gravy spot, but its worth taking a couple months to figure it out.
Both and neither. It is not 'you take as much as you can nor does it 'depend'.
Apart from the fact that there is no reason to eat protein to 'feed' fat mass - the difference that it makes (20-50g for someone who is upto 20% at 250lbs) is not the difference between muscle gain and not.
That said, it is certainly better to be higher than you require than lower - so the safe side rule suggests that TBW is sensible (although protein has very little to do with this really, it is a very simple way of managing it).
Then you have to account for goals, drugs, training, everything else.
If you eat little in the way of CHO - you will need to consume more protein than if you eat plenty (insulin).
However the difference (in protein requirement) that CHO inclusion cause is NOT the difference between ones LBM and TBM.. it is significantly more than that (following the 'obese 250lb guy' example i gave rather than the 'guy who cannot get out of bed' as per your example).
IME a trainee who is natural and eats a mod/high carb diet then 1g/lb TBW is fine.