Like in money, or economic activity as well?

The biggest issue in many places is corruption. You give them money and someone steals it. Build them a factory and some mob bosses take it for themselves.

Probably. Most countries secure their borders. It seems a bit nuts to not secure them.

It seems even more nuts people would make it a political issue.

What do you want to happen? Let everyone in so you can feel somehow morally superior to others? These people would be at a disadvantage to those who immigrated legally. Is this what you want? To use a bunch of people having hard times to feel superior to others? You don't want them to have an actual good life instead?

But whatever, the actual immigration debate can be a separate issue. Perhaps you want more people, perhaps you want less. Figure that out later.

The first step is to plug the hole in the boat, after that you can decide which direction to sail.

I moved country pretty much for this reason.

But I had to move back because my mum couldn't afford to live anywhere. So I brought half her house from her and we're roommates.