The listing agent represents the seller first and is charged with getting them the highest price.

You will need a Lawyer for all the Contracts items, and if real estate is involved, a Title Company too.Lawyer and Accountants will charge by the hour, mostly because a $100k purchase has less to look at then a $1mil purchase.

For recent purchases: less than 3 years, you probably have to grow with them and think about how can you maximize returns: maybe ADUs, or Coin-laundry or e-pay, renting space on the property for storage, air b and b or mid term rentals, splitting the lots, Tic sales etc... or value add to increase appreciation faster!! 

Thank you for the valuable information @Mike Lambert  Aside from banks, is there other institutions we could get the refinance faster here in Portugal? 

Faster is better but you don't typically need the fastest available. 

Each time I bought one, because I was receiving cash flow, I was able to save up for the down payment for the next one a little bit faster.

Some will just charge you the interest, some will charge interest + points, some will just want a % of the profit at sale/refinance. 

How are the additional fees they charge?

I'm in East Tennessee and we just had a guy that was doing the same thing, and is now facing state and federal charges and some people have received some restitution.

Arizona's water supply from the Colorado river is being depleted faster than it can be replenished.