Conversion of (very) old Clyde Combustion boiler to wall mounted modern condensing system

Dear All,
SWMBO has threatened proceedings and all sorts of other dreaded threats if I carry on procrastinating on replacing our CH system so I have now had to put nose to grindstone! We have an 1880s 8 'bedroom' Victorian house on three floors with small cellar. It is pretty, damn cold as it faces W-E and has large areas of windows front and back Needless to say, it is 9" brickwork and has (redundant in all but two cases) chimney flues to the fireplaces in 6 bedrooms and two receptions which I shall, have blocked up. There are about 5 rooms per floor (four major and WC bath etc) Rads all over the place - 5 on top floor - one in each room -likewise on first floor plus one on the landing making 6 - on GF one in each room except SR which has 2 (which I wlll replumb in series so as to be controlled by the one RF valve)
In all the rooms (as opposed to landings etc) there are thermostatic rad valves which have 'Drayton' and BS6284 on them. Quite a few of these have failed 'open' so putting on the heating wastes heat in those rooms which are mostly unoccupied now that the kids have flown the next (mostly but they do keep coming back for odd weeks!)
The whole lot are on one zone valve controlled by a single old stat in the hallway (the coldest part of the house).
The boiler and DHW cylinder are both in the cellar with and open vented system up in the roof void One rad acts as a 5 min override for the boiler directly off the primary flow and return
The boiler is supplied by air via both the Subfloor air vents (a howling gale) and a chimney flue (which was originally supposed to be the flue for the boiler but the plonker that put it in use 90 degree bends and a pipe too small and not insulated so now it acts as an air source!) It is also vented by a large insulated flue which I hope to make redundant
Proposal
Get shot of the boiler which is cast iron, big and really not efficient.
Put on a new, wall mounted modern condensing boiler with a balanced flue extension going up through the floor of the room above the cellar (a shower WC) close to the outside wall in the present position of the current 7" insulated flue and vent it (at just about floor level - 6" above external ground level) outside. It may be that there are minimum heights above ground for such flues and for a balanced flue the vertical 'rise' will no doubt be about a metre or so at max (but may be wrong)
This boiler will be a direct substitute for the existing one and free up much space some of which I considered using for a buffer cylinder to increase the efficiency of the boiler but am not sure that this is going to be cost effective with so many radiators to heat up (see later I intend to have only one room heated most of the time which would make having a buffer more sensible)
I suppose the buffer can simply be a large cylinder with a supply pipe to the top and exit at the bottom. (See later questions)
Now the trickier bits... I have been researching the Honeywell CM Zone valves with RF controls
It seems to consist of the following a radiator valve eg theHR80UK CM ZONE RF TRV HEAD (or perhaps in my case 4 as I have 3 zones plus the rest of the house as zone 4 The receiver for the boilerHONEYWELL R6660D1041 HC60NG RECEIVER that appears to act as controller A HONEYWELL T6667Z1080 CM67Z ROOM UNIT that acts in place of the existing timer and will allow me to have (I hope) four "zones" 1) the whole of the house not individually zoned ie all bathrooms, landing, hallway, second floor bedrooms three first floor bedrooms and kitchen 2) My "office" - a first floor bedroom converted to office 3) the sitting room Ground floor 4) the dining room on GF also used as office mainly
As I understand it, this can be done with normal thermostatic valves on the whole of 'zone 1' which can be altered manually to suit and will be controlled by the basic thermostat in the GF hallway where the CM67Z will be and the HR80s in each of the other three zones I presume the receiver is with or connected to the boiler!
So here are my questions...
    1.    Is there a balanced flue boiler that one can put in a cellar and have the flue stick up vertically about a metre before it goes out through the wall?     2.    if so (and I am told they exist) what is the best make?     3.    Is it likely to be compatible with the R666... receiver (probably / surely?)?     4.    I am concerned that my 'default' zone 1 may not be feasible as it will simply be a timed on off based on one thermostat in the hall but cannot see any reason why it should not work     5.    The balanced flue will have to go through a wooden floor - will this need special protection with Asbestolux etc or is it cold enough not to worry with these new super efficient boilers?     6.    I take it that balance flue boilers need no 5 min overide as does a large cast iron one and that I can dispense with this and integrate the rad with the normal flow and return?     7.    I want to do most of the work myself except, obviously, the actual installation and commissioning of the boiler. By that I mean I want to do any non-gassy bits and all the preparation for the gassy bits like getting rid of the 5 cwt old boiler etc and to have a Corgi man do the rest so do any of you know and recommend such a person in SW18?     8.    Is a buffer needed/advised?     9.    If so where to get? (there is 10 m of head to the tank)     10.    Generally, am I headed in the right direction?
Chris
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