Reddit mentions of Double Headphone Audio & Charge Adapter, 2 in 1 Dual Splitter Cable Design for Calling & Remote & Charger & Music, Compatible

I use to bike commute from Prospect Heights to Midtown. Not quite sunset, but I'll give you some tips.

• The ride is long, and in winter your hands will go numb. Also, as it gets dark so early you're going to want to invest in something that will make you super visible to drivers. I used a few of these (https://www.amazon.com/LED-Reflective-Belt-Rechargeable-Lightweight/dp/B00N1SN7I0/ref=sr_1_6?ie=UTF8&qid=1483995375&sr=8-6&keywords=visibility+running)
  
• For me, biking in Midtown was the worst. Cabies and drivers aren't expecting you. I had to be very careful there until I got to the protected lane on 1st / 2nd.
  
• Invest in panniers, it made bringing my laptop much more enjoyable. Before that my shoulders would get soar from the weight of my backpack. I used these (https://www.amazon.com/gp/product/B0044U8W3E/ref=s9_acsd_zwish_hd_bw_bEHNt_c_x_w?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=merchandised-search-8&pf_rd_r=PHZ5YEF0BQTB493HNW43&pf_rd_t=101&pf_rd_p=df4b1a7a-041b-544a-87d6-d9451ee55b2c&pf_rd_i=3403421) for over a year until I moved to Chelsea and stopped bike commuting cause I could walk to work.
  
• I was able to bring my bike into the office, not sure about bike parking. Limited at best and mostly on street which is risky. You may have some luck with garages having space if you ask around / basement space if you ask your building management. Garages over a certain size are required to have bike parking (http://www.nyc.gov/html/dot/html/bicyclists/bicycleparking.shtml#indoor) but you might have to fight for it.
  
• Biking was the best decision I ever made. I got to work in a better frame of mind, and got home happier than I ever did taking the subway. Would recommend it. But stay safe!

I highly recommend a rack + panniers. I just switched from using a backpack to a rack + panniers on my commute and it's MUCH nicer.

I got these:
https://www.amazon.com/Ibera-Bicycle-Touring-IB-RA4-Frame-mounted/dp/B002T5H8MW/ref=sr_1_1?ie=UTF8&qid=1473272148&sr=8-1&keywords=bike+rack+and+panniers

and
https://www.amazon.com/Ibera-IB-BA8-Bike-Panniers/dp/B0044U8W3E/ref=sr_1_2?ie=UTF8&qid=1473272148&sr=8-2&keywords=bike+rack+and+panniers

For less than $100 bucks you'll be much more comfortable.

I've been happy with these panniers, plus they match your setup - IBERA

7 yr olds are tricky with Scouts, they don't really do much camping, and most of it is car camping. I suggest cross posting this to /r/BSA as well.

I picked up a nice tent at REI that my son and I used camping. Kelty Discovery 4. Might get a little cramped with 3 people + gear. It wasn't expensive at all and it handled a really good rainstorm the first time I used it.

Sleeping pads for child size is going to be hard. I would just get a regular sized one and then throw down a fleece blanket at the head area so they don't have to lay their head on cold plastic. I recommend the fleece blanket for everybody, it rolls right up with a sleeping bag and I really hate cold plastic tent floors.

For child's sleeping bags, no idea currently. I ended up getting my kids Olive Kids from Amazon before I considered Scouts. So far they are holding up well.

Backpacks are going to be a really hard find. Even frame packs don't fit well until they are pre-teen. Try going with a larger Jansport type bookbag with a larger second pocket. Luckily the clothes don't take much space, and gear is limited to flipflops and scout books. My son packed all his gear in a pair of bike paniers

Ibera 2 in 1's get good reviews

I have their standard panniers, and haul a lot of heavy grocery loads every week, so far they're holding up well.

That Dawes Lightning you posted has a rear rack. (Google the Dawes by the way--it looks like they're $249 new).

Then you just get a crate--like milk crate, coca cola crate etc. and zip tie to the rack.

http://i.imgur.com/yy1ic.jpg

http://www.bikehacks.com/.a/6a0120a7ed5f9d970b015434e82cf6970c-pi

Or, if you want to be more proper about it, you buy "pannier" bag setup:
http://www.amazon.com/Ibera-IB-BA8-Bike-Panniers/dp/B0044U8W3E