New here and a few questions.

I have been lurking here for a little while and finally decided to post after completing my first 10+ mile ride yesterday! A little background: I am married with two beautiful wild boys 4.5 years and 18 months... DH and my elder son are bike obsessed so for mothers day this year I told my husband that he needed to get my bike into action complete with child seat for the babe. Its a 1973 Schwinn Collegiate. Originally a 5 speed DH converted it to single speed. After the first ride I was hooked. While I love my classic bike it's basically a cruiser and I want to do more fitness rides on my own without the kiddos. I purchased a (don't judge me) very inexpensive single speed bike from target and have upgraded several parts to higher end parts. I can't afford a nice bike right now but this serves its purpose nicely for the time being. One of my goals is to commute to work. I only work one day a week and there is a paved bike path conveniently between my home and office. So far I have logged several short rides both with the kids and without (anywhere from 1 mile to about 4 miles) but yesterday I did my longest ride at about 11 miles roundtrip - this was my test ride for my commute and I'm so proud I was able to do it!!! My bike does not have a bottle cage so I wore my husband's camelbak. Do any of you ladies have an opinion on water bottles vs camelbak? I really liked it actually. Also the next part I need to upgrade on my bike is the saddle. I definitely need womens specific as trying to get into a more forward position was quite uncomfortable. I'm looking at the selle italia diva gel saddle. Does anyone have any input or advice for looking for a saddle? Thanks in advance! I'm excited to be here!