Just keeping note of what I've been playing around with on my local copy.
* Added 'Fertility Idol' item.
* Added 'Your Gold' text element to gang management screen.
* All characters have age / age range based on information on the character they are based on and/or physical appearance. (Coded restriction on age relaxed to match 'actual' age of characters).
1) This is better suited for Mod section and I'll assume you wouldn't mind some sort of a comment since you can locally make notes using a pen and paper.
2) About the Item. All modders and most users in here can create an item in under 30 seconds. There are also some item packs and addons in the mod section. If you are fishing for the ideas, I can offer my approach. I added some new items and created "Levels" on the existing once, for example a lvl.1 ring that will add 3 to girl's beauty and 5 to charisma is priced at 1000 while a lvl.10 ring that would add 50 to beauty and 60 to charisma would be priced at 80 000. I have applied that to all appropriate items. The reason for my approach is that I like really long rounds, have about 30 Random girl variations and over 1000 unique girls (around 99% downloaded from modders and 1% made by me), this allows some kind of an outlet for your cash when you start making more or much more then 100 000 per week.
3) On "Your gold" element at gangs screen. That becomes obsolete really fast since the gangs are cheap... but it doesn't hurt anyone

4) Coded restriction of 17 has never bugged me but maybe it would be better to restrict age to 18 and display something similar to ? ? ? (-- for example) for anything less like with over 100 year old girls? Be careful with "age range" restrictions for Random girls or when you kidnap "Wife and Daughters", you might get stuck with a mother that is younger or not much older than her children, unless you are planning to edit the nopay script as well.