Welcome to bikeforums! I'm a 55-year-old commuter. Do not worry about the weight of the bike...especially if you live in a relatively flat area. A 28-ounce waterbottle, full weighs about 2 pounds. Two water bottles, about four pounds. The percentage of the "extra weight" of one bike over another is a small percentage of the total package with rider.
Two years ago I bought a Charge Plug, which is similar to the Fuji Tread. I have drop bars, but have them raised a bit. I am very comfortable.
My main commuter for years was an old mountain bike. With higher-gearing and 26x1.65 road slicks, it is a fast, comfortable bike, despite being around 30 pounds. I then picked up an old Nishiki 12-speed with 700x23 tires. I eventually went to 700x32. They were more comfortable and worked better on the occasional loose dirt.
My new main commuter is the Plug which came with 700x32s. My third pair of tires, which I just bought are Continental Touring IIs which seem more like 28s. You wouldn't think 4mm would make a difference in loose dirt, but it does.
Any way I ride for fitness, so I figure, any extra weight is an extra workout. But really,the weight is not an issue except on long gradual inclines, and even then...not so much. The old MTB commuter has very low gears, and my lightest bike, the old Nishiki International 22-ish pounds is the toughest to climb steep hills because of the lack of lower gearing.
If you are planning on sand or gravel sections, 32s are a minumum. but a smooth 38 or wider tire would be better (make sure they will fit).
Also, in my experience over the years, my opinion is that aggressive, blocky tread is only needed in mud or snow. And also the "hybrid" street/trail tires that have a smooth center section, but knobs on the side are a poor compromise. They roll smooth and easy on going straight, but when cornering you transition to the knobs which grip less and make for poor less secure cornering. Merely letting some air out of big, smooth tires will help plenty on gravel.
And as far as padded seats; most people seem to do better with firmer seats, but after commuting seriously for 25 years, I do better with a padded gel seat cover on my Charge Plug, TWO on my 83 Nishiki road bike, and a padded, gel seat with springs (and a long nose) on my MTB. I've had no issues with chafing, nor my man parts. However, everybody is built and shaped differently.
No matter what you ride at first, you will discover what works for you and what doesn't. Your second bike will be a better purchase.
Good luck, ride safely and go, Go, GO!