I found an answer to my third question, but not on 1&2:

1. How does the blockchain technology make the rental process less costly? The application costs money on your site, plus actioning system tends to make prices higher. Also, when I pay rental payment to landlord through your system, I will need to pay some fee? It is more costly than if I pay in cash to my landlord.

2. The actioning system brings benefits only to landlords, doesn't it?