Hey @Sami1,
I have worked in the Portuguese real estate industry for over 5 years. What I can tell you that it is important to work with a licensed real estate agency and I would always advice you to work with an independent lawyer that can advise you with regards to your investment and your golden visa. Also, try to work with a real estate consult rather than a regular real estate agent, who can advise you on the right investment that fits your personal situation and preferences and is interested in helping you to make the right decision instead of trying to sell his/her listing.
I think if you decide to invest in a property in a low density area, you would need a local to manage your property. Sometimes the vendors / developers offer a guaranteed return nett of costs (so you don´t pay utility bills / condo fees) for an agreed period of time (4 or 5 years). But you can also buy a property and have it managed by an independent property management company. Usually the property management companies or holiday rental companies will charge a percentage of the rental income and you would have to bare the costs for the utility bills and condo fees etc yourself. In this last option you would be a bit more flexible on using the property yourself.
In any case, your lawyer would also advise you on this management contract.
Hope it helps!