The Evaporative Cooling Site

Yes they perform better for a number of reasons. The airflow is generally much more which gives much more cooling. Because the portable cooler is located in the room, a lot of the airflow comes from the room. This air has already had its cooling ability used up.
Air can blow right past the cooler straight into the room without being cooled. This hot air fights against the cooling produced by the cooler.
Overall rooftop arid wall /window evaporative Coolers perform better than portable coolers.

If water is coming into the room it could be due to woodwool pads shrinking away from the frame, allowing the air to pick up water droplets. Alternatively a component may have come loose in the cooler. Other possible causes are that the cooler has too much airflow or uneven waterflow across the pads.

I have an evaporative cooler and I noticed that the pads have dry patches.

This generally means the water distributors are partially blocked and need cleaning. However, the same symptoms can also occur if the water level is set too low. So check the manufacturers recommendations for water level. If the weather has been extremely hot and dry it may simply be the design of the cooler.

A house can be fitted with a ceiling air relief grille (often called an up duct). This allows the air to relieve through the ceiling space. Depending on the size of the cooler and grille, a single grille will generally allow the cooler to run on low or medium speed, while more grilles would allow the cooler to operate at any speed. An air relief grille will allow the cooler to operate without opening windows which is a security advantage, and means you can leave the cooler running when you pop out for a short while, so the house doesn’t get hot while you are out.

When cleaning the cooler, pay particular attention to ensuring no debris is caught on the sealing surfaces of the dump valve. If the seal shows signs of perishing, replace it.

Legionella bacteria require hot moist conditions to multiply, and need to be carried in fine suspended water droplets to spread. The water temperature in evaporative coolers is too cool for the bacteria to multiply. Further a well maintained evaporative cooler won’t spread the bacteria even if they have entered the cooler. If you still have a concern, then I recommend either a dump system (dry tank system) of some sort as this allows the tank to dry out which kills bacteria and algae. The alternative is an ozone purifier.

If you have a portable evaporative cooler you need to locate it as close to an open window as possible. However you need to try and open the window in a way that most of the air goes through the cooler, and doesn’t blow straight into the room. This may require you to lift the air conditioner up so it is in line with the window.

You also need to try and direct the air towards where you are sitting. Because some of these criteria conflict with each other, it is difficult to get good performance from a portable cooler.
If you permanently install one in a wall or window, the performance will be significantly better. Some (but not all) portable evaporative coolers are designed so that a float valve can be fitted. Contact the manufacturer to find out if yours can have one. I don’t have any contacts in Geelong, so I can’t help you with the name of anyone who would help install it. (Generally when this is done it is done as a DIY project).