New Here- some questions

Hi all- Really short bio on me: -Have played semi-pro sport in the past, had my daughter at the age of 30 and basically have not done a thing in the last 3 years (I'm now 36). Decided to join a Master's Club because they swim at the same time my daughter swims (by the way she rocks and is doing her first competition this month!). Ok anyways. -LOVE our coach we do some interesting drills, feel like in 2 weeks my stroke has improved dramatically. Questions: 1. Is it normal to be so sore all over after these practices? I swam 3x this week and my whole back is sore- thinking that perhaps I'm in worst shape than I thought but will I build tolerance as I did with other sports or does continue to be sore throughout time? 2. Right now I'm swimming with fins and feel as though I'm swimming 'ok'. What to do to get enough strength built up so that I can swim at the same rate/speed without the fins? 3. Although I'm sure I'm burning calories, I have seen NOT a move with my scale. Would ideally love to lose 10 lbs but wondering if this is just not enough for cardio since this is my first shot ever at swimming- sorry for the lame question here- I'm basically really loving it, like the 'therapy' of it, but would also like to benefit from it by losing some weight. My stomach and arms have gotten a workout but will my thighs benefit as well? I mean, I see all these women swimmers with amazing bodies but do I need to swim for 15 years before I see results? 4. Lastly, how long did it take you guys to cut your time (this is my competitive side here)- I'm not fast- 36-40 seconds for a 50 yard swim and was wondering how I can work on improving my output so that my time comes down without letting things go astray (stroke, etc) I still get fatigued pretty quickly and am working up my endurance and frankly I can't wait until I can swim 200 m without stopping for breaks at the 50 or 100 mark Thanks! :) Look forward to getting to know you all. :)