I took a walk along Rajaprasong and Silom and found the blocked roads filled with temporary carts and stalls selling food and souvenirs, especially "Shut Down" Bangkok T-shirts.

I wonder if these stall owners have to pay any form rent or service fees. And if so, to whom do they pay ? Police, Government or PDRC ?

Most likely PDRC I'd think, but maybe the plod comes 'round for handouts as well, usually not so much for temporary setups.