>Is it possible to run a working webcat (although with very limited resources) with just a MM/51-E board alone ? or it\'s mandatory to buy an MMC or a RAM/FLASH peripheral board ?
It is possible to run WebCat without MMC, RAM-1 boards if AT24C1024 EEPROM is installed into a DIL-8 machine socket on MM/51-E board.
In that case all the files served from serial EEPROM.
> Does the MMC board come with the cable to connect it with the MM/51-E board ?
The MMC board can be installed on top of MM/51-E without a cable. If you need a flat cable it can be purchased separately.
> Does the MMC board already include the MMC or it has to be bought separately ?
separately
>To build a fully functional WebCat server is it ok to buy (in addition to the MM/51-E card I already have)
1) MMC-RTC-1
2) MMC card for the above one
YES
> Last question, is it possible to change the I/O status of the MM/51-E board via commands like "
http://192.168.0.1/lights.asp?CLR=P1.0"
without any additional board ?
It is possible if your setup has any file storage ( MMC, RAM-1, AT24C1024 EEPROM) to keep lights.asp.