I managed to get my first version of the board working using a PIC24GB002.

For this board, PIC was communicating directly with the AT commands of the ESP (sending AT's and parsing response). the 3 end-points i created were :

/led/clear

/led/print?text=<TEXT>

/led/set-color?color=RED|GREEN|ORANGE

The problems with this board are

1. Writing and parsing AT commands on the PIC cost me with precious CPU cycles, which in turn caused the display to flicker every time i sent a command to the ESP over the network. The PIC had a 16mhz oscillator connected to it but even with 16mhz the screen was still flickering ever once in a while when i typed a new message
2. PIC24GB002 didnt have enough IO pins to support the 160x24 display (3 IOs for each row + 4 shared across rows = 13 IOs pins needed)

Iv'e decided that for the next test board i will -

1. Use a larger PIC - PIC24FJGA006 which have more than enough pins to support the larger 160x24 display
2. Remove the parsing and REST request processing from the PIC and move it to the ESP
3. as a 'bonus' - i`m gonna to replace the old 16mhz oscillator with a new 20mhz one - which will hopefully eliminate the flickering completely

I came up with this design -

and this board -