I haven't seen any yet that do 10% down on non-owner occupant purchases, but that is awesome if that exists. 

The existing homes are too small and would require a large expansion, at which point it would just be better to build new. 

Also, if you have anything in your existing escrow account, you will get that back within a few weeks of closing.

When analyzing a new build/“build to rent” property as a rental, what percentages/amounts are others using for:-Maintenance/Repairs-Vacancy-CapexI’d assume it’s less than than existing homes, but by half or is it safer to use the standard percentages?

You'll find a ton of kind, supportive, and helpful people here.Are your existing 7 properties currently in Chicago? 

If existing houses are cheap relative to land and constructions costs, and supply is high, it may not be worth developing even if the agency says "do whatever you want".

Other options include partnering with someone with better credit, negotiating seller financing, or leveraging existing property as collateral.

They need to do all their due diligence including understanding the value that will be added by the ADU, the finance options available, the consequences of adding the ADU (rent control, property taxes, rental limitations, etc), etc.Good luck As with all things, it depends on the investor and the equity.If they are able to leverage existing equity to buy it under a HEL or HELOC, then they are adding equity with no out of pocket expenses, and adding immediate and longterm cashflow to existing stock.We like ADU's because there isn't more land being created in our city that is landlocked...but there is more density available to those with large lot under-utilized sfh.In my market, it typically costs $2 to add less than $1 of value on single build ADUs.  

You mention going on title and taking over the loan - is there an existing mortgage?

Living, but either way you could try speaking with existing owner/operators groups in the greater bay area, or even central coast, looking to expand their portfolios for a joint venture.