Help: Alarm Requirements....options, Costs, Installers, Equipment...

jig

Calling all alarm engineers and people who know about alarms............I currently have the following alarm setup which was a Secon(!) install and is now bells only (was under redcare):

1. Ademco Keypad(near doorway) and a Control Panel upstairs in airing cupboard.
2. Secom Bell Box
3. 6xPIR sensors
4. 1xViper for front window
5. 2xPanic Buttons
6. 3xDoor Sensors
7. 1xInternal Sounder

Now I think this Alarm is too old. I wish to update and add some more features however re-using some of what already is installed (eg wiring,etc). I have put together a list:

1. Ademco Keypad(near doorway) and a Control Panel upstairs in airing cupboard.Replace with Menvier TS900+ or TS2500+? and with Menvier LCD Star Keypad
2. Secom Bell Box Replace with NEW Bell Box
3. 6xPIR sensors Replace with NEW 6x PIR's
4. 1xViper for front window
5. 2xPanic Buttons
6. 3xDoor Sensors
7. 1xInternal Sounder

Additional Items:
8. 1x extra PIR sensor (downstairs in kitchen, not to far from control panel location above on first floor)
9. 1xTelephone Dialler
10. 2x Smoke Detectors
11. Menvier TSNETProx with Key Fobs
12. External Dummy Bell Box

QUESTIONS:
a) What suitable equipment does everyone recommend for 1 - 11???esp which PIR's?
I already have a TS 900+ and the TS 2500+, does the TS 2500+ take a lot longer to install?
c) How long would it take to complete all of the above work by a trained professional?
d) I already have a local guy who does private work and works for the local security co, but is charging £175 for the day!!(i think this is too much)
e) Does anyone know a local( Loughton, Essex) trained person to fit all the above esp if I am planning to source the equipment?
f) Do I require any other equipment or any other work that may also need to be carried out?
g) If installed privately can i get monitoring later if required?

Apologies for all the questions but need to get this right, thank you in advance for all the help and advice.

Jig:)