Once established in these deals did that income provide a baseline to become an investor? 

I wouldn’t do the extension just yet wait to get that property established the way it is first then maybe down the line do it.

I do not have an established relationship with a contractor I trust and this is the missing piece to my puzzle and if I really had to I could do the work myself, so I feel this will allow me to not feel pressured into making a bad decision. 

As I am interested in keeping long term established good paying tenants even if I leave a little meat on the bone...

If you are looking for a traditional turnkey company (one that buys, rehabs, rents, manages, then sells the property to an end investor), there are no established companies that do that.

Ask them about whether they can provide anonymity on public record, assist you will establishing operating companies and if their entities will roll into any future estate planning if the need arises.

The commercial property is an established Neighborhood Shopping Center and the owner is looking to sale.

I have four in Cleveland from 1930 to 1950 in established nice neighborhoods but I am constantly getting calls on basement issues.

Based on what the previous owner paid, their improvements, & relatively short hold time, I know this is not worth asking so I'd like to get a more concrete way of establishing my own pre improvement value and ARV.Any other ways I could/should be looking at this?

If you expect an influx of utility expense, then adjust pricing.If you're concerned about property usage, then establish clear rules and boundaries, with a method to enforce (without encroaching) and have penalties clearly defined.Best of luck to you.