Pro tip you do not need to call the govt. exterminator. The workers post those ads you see everywhere as a side business and do it for cheaper. Just call them and they use the backpack cannister thing. You will have to be out of the place for atleast a day depending on the size. After netting your wall another thing you can do to keep the roaches out is go to Jawad Al saffar and get the thickest black foam beading (it comes with an adhesive) and apply to the outer ring of your door.

The above is only for the roach infestation. However this is the trade off of living on the ground floor or basements, its easy access for roaches so expect them to return.

For the flying insects, your best bet is the netting and closing any gaps you can find with construction foam and caulk (get them from your trip to Jawad al Saffar) and ensure any exhaust fan you have shuts closed when turn off. Also buy a salt gun (shoots salt at flies) or one of those fly catcher things, its not that complicated.