if you are training to race then alternate 2 days intensity and 1 recovery day. if youre just riding to ride do whatever you want frankly, thats straight forward.
are for cadence different bodies like diff things, not right or wrong there. i am 123 lbs, 6% body fat and should technically favor a high cadence style, but my aerobic capacity isnt world class (vo2 max is 59.5) and i find i produce higher average speeds and have greater by turning a low cadence (not that my leg muscles arent shot be the end of a hard training ride or race, because they dff are)
edit: dont forget the importance of eating alot of protein to give your body what it needs to receover and build muscle, thoug not knowing your body fat % noone can say whether losing weight versus gaiing muscle is "right" for you. also, yes your legs might feel tired, but you have to push to the next level and suffer, then recover fully to improve fittness