Dynamic Web Pages And NAFS_writefile/readfile


1- I have a web page that displays an image, now i would like to dynamically change that image with one uploaded via ftp.
As I use pbuilder to convert my page to c, the default image displayed is converted to variable at compile time, is it possible to dynamically convert the new image to use it?

2- My application write to files in flash0 each time information are modified from web pages, and I use NAFS_writefile/readfile to save some struct type table to flash, actually i cast these struct type tables to char* when calling NAFS_write/readfile. My question is: does my struct table, after being written to flash, will be well formatted if i directly read from flash to my struct table?
typedef struct
char foo[5];
int number;
} my_struct;
my_struct struct_table[2];

i do NAFS_writefile(…,“FLASH0/filename”,(char*)&struct_table[0],…)
then NAFS_readfile(…,“FLASH0/filename”,(char*)&struct_table[0],…)

Will the content of struct_table be exactly formatted as previously defined?

3- What is the delay between 2 consecutive call to NAFS_writefile/readfile functions?