I'll suggest to use NE556 instead of NE555, bcus it contains 2 pieces
    NE555 so the amount of chips required is halved.

Well, once you can build a NOR or NAND gate, you can build anything as
far as logic goes.  (there'd still be trouble trying to do the EEPROM.)

    I think so you need about
    10 cubic foot to place your design (instead of about 18).

Nah.  Haven't you seen the recent Micrel (?) ads?  A 555 in a 5 (?) lead
SOT23-style package (or was it the even smaller one?)

 :-)
BillW