Bonus questions:1. 

Together with my girlfriend (who is an architect) we also bought our first small building in Brussels which we are currently transforming into 3 appartments (expected to be ready by end Q1 2016)happy to share insights and experiences!

Also, have to know the local practice on 100 for the garage, and what if someone was not interested... so that income may be tough or a "bonus" for a one year lease to attract a good tenant...

If everything is mid $500k's I'd shoot for $550k for arguments sake, consider anything higher than that a bonus.

Like you said, anything outside the peak time will be bonus money. 

I am also struggling to wrap my head around whether being our own landlord is a double bonus in this situation, and should make us willing to accept lower returns , or even negative cash flow at first, because otherwise, our $36k annually in rent is just gone every year. 

Another bonus is that it has tutorials for how to use and apply these calculations using real world examples.

Those increases are your bonus' if they occur and you should not pay the seller for what they did not do.I would still consider the rent of a unit that I was to occupy.

I currently get paid $50/house plus a bonus for leasing/lease renewals. 

Pay them enough to keep them from starving ($10 an hour) and then bonus them $7.50-$10 for every appointment they set that is kept (you actually meet with the prospect).