And...
(1) Yes*
(2) Yes* (Depending on what the "Existing Cable Hook Up" Is, Remember, He will need to run a total of 4 lines to the multi-switch from the dish).
(3) Possibly no but possibly yes, "Well"??? Basically the 4x8 should be powered using standard RG6 from the Wall outlet to the Multiswitch so again, standard installation rules apply
(4) Yes* (As long as by "Cable Box" you mean a box with all your cables in it) Again, remember that the Tivos need 2 lines run "directly" From the dish to them, the standard receivers need 1)
(5) Yes*, of course

(6) Yes*, of course
We actually can charge up to $3.50 per ft. for burying the cable, Its cheaper to do it yourself (Sounds like thats your plan anyway). Now if he is trying to charge you for the cable itself that is not right, you get up to 100 ft per run of standard RG6 Coax (2 per Tivo, 1 for the standard, actual cost is around $55 - $60 for a box of 500' Dual w/Ground).
I actually just picked up a wall fish, havn't carried one for a year (remember, Wall fishing is chargable @ $45+ per hour). As to running the cable on concrete, we have no way to do that either, The nail in clips don't hold and the screw in don't work very well (I would probably give it a shot if you wanted me too @ no extra charge, no promises though) thats more of a do it your self type thing. However, most of the time you can tuck the cables up under the siding, otherwise on the siding it goes
*Yes means he should do it at no extra charge