Two identical homes located next to each other would come up with the same value, even though House #1 was just renovated to a very high standard and House #2 hadn't ever been renovated since it was built in 1949.I always tried for an identical (or nearly so) beds, baths, sq ft of living area, garage and acres. 

I would be very careful with a lot of course or guru in general right especially a price tag like that what I would always recommend reading the contract and see who is the person more in favor and if its not you then dont sign up very rare to see someone actually benefit from a course.

Best of luck!

Its much harder to turn a property around in 6 months expecting to have 100% of your money returned back to you - but if you focus on the right property focusing on highest and best use with an ADU add (like mentioned), in-fill/lot split, or other rehabs - then hopefully a semi-decent property like that will perform like a champ in a few years. 

What seem to be the best zip codes for rentals?  

What would be my best route to take if we need additional finances?

Here in the USA you need what's called a "construction loan" and it's also very hard to find a company that will insure you if you're a newbie.

Find out which filters are best for your furnace, purchase a year's worth, write the installation date on each one so the tenant knows when to swap them, and inspect regularly to verify it's happening.

I would say that is about right.And in the end, as @Arn Cenedella wrote, it is as much art as science...so even the best killer spreadsheet only takes you so far. 

I would consider selling, i’m not necessarily saying you should, BUT only hold if you have a very strong belief in the appreciation of this property.