How shorts look depends on your build. I'm a lean guy. I've had good luck on Amazon by looking around for brands where middle-of-the-country Americans complain that the sizing is too small.
Here is a pair that I like. The material is a very light nylon. This means that it's good when you are likely to sweat. Also good for travel, as it packs super-light:
https://www.amazon.com/gp/product/B08SC8DVDX/
Here is a similar pair. But this material is heavier-- more of a terrycloth feel. It looks like it might have been redesigned since I ordered:
Try this smart tape!
It can not only record your circumference, but also calculate the body fat rate, and at the same time, it can also calculate the more accurate body fat rate in combination with the body fat scale compensation, allowing you to better grasp the changes in your body.
https://www.amazon.com/Slimpal-Bluetooth-Retractable-Measuring-Bodybuilding/dp/B09CDNXY9N
Re: sit-ups... I like an ab roller even better if you feel like investing in one. I like this one a lot. https://smile.amazon.com/dp/B00B1N0R6C/ref=cm_sw_r_apan_glt_fabc_0TG6MR51X6EA403YEESF
Sugar, damn, they sneak it into EVERYTHING. 30-35g per day for guys is a recommended max. That includes natural sugar too: honey, fruit, etc. Just start reading labels, you'll probably be shocked at how much you were eating unwittingly.
this one works for me but I'm not doing anything too wild: https://www.amazon.com/Reebok-Professional-Aerobic-Deck-Black/dp/B01LYFX9WX/