The newbie has questions

Hi Daniel

First, 47 is not senior (also 47)!

Beyond ensuring adequate protein and fat intake (0.6-0.8g per lb of ideal weight for protein, and 0.3-0.45g per lb ideal weight for fats as minimums), macros are really a matter of personal preference and satiety (what keeps you feeling satisfied). Don't let yourself get too bogged down with those things at this early stage, you can tweak as you go and work out what works best for you.

Some of the initial weight loss is likely to be water weight, so once that's off, it slows. Sorry, but it's not muscle weight gain (even under ideal circumstances, muscle gain is really quite slow). If you're new to training, and have been increasing the intensity, you will retain some fluid for muscle repair, and that can stall scale weight loss. Don't worry, so long as you are at a calorie deficit (ie, sticking to the calorie allowance MFP gives you, plus at least half of cals burned exercising) you are losing fat, and that will eventually show on the scale. Frustrating, I know! But just stay the course. If you're still not seeing any downward movement in a few weeks, the first thing to check is the accuracy of your logging, to ensure you're not eating more calories than you think you are.