wtf no to all of them in the first second, seriously bad deals
even the 'losing a limb one' which sounds good at first, but then you realise the average person has very small chance of losing a limb... and even if you did at about 50, it wouldn't be worth the quality of life you lost in the years leading up, in which you'd be treated like a leper because you are 'green and scaly'
"Be able to breath under water but no longer be able to breath normal air, and have webbed hands and feet?" .. the point is? Basically 'would you become a person-fish' er.......... you do know there is such a thing as scuba diving? Or even snorkling if you don't want to take ages kitting up?
for the second section, I would have immortality at the cost of a family member yeah. there's some right mofos on one side
to the gender thing... i'd do that cause within the next hundred years there'll probably be some foolproof way to change genders. what's 100 years compared to the rest of your never ending life?
no to species....... dunno why anyone would bestial creeps
to the third section.. i don't even get the third section. why would you want to :S

. What you say is true for some really basic medications, but not for the vast majority of medications. In fact, it's true for less medications than you may think. Your body grows tolerances to various medications because of this fact. Especially when dealing with modern medicines (congenital conditions, geriatrics, plastic surgery etc) they are continuous things.
It's also why geriatric medicine is such a big field now compared to before.