Central Heating Pump and Immersion - Help please

[pop80_uk]

Hi all,
Hoping you can help and offer some advice, basically I need to fit a new pump, the old one is 11 years old and making some terrible noise! I also need to fit a new immersion heater as the old one no longer works.
Current pump is a Grundfos UPS 18-60 and Immersion is Sector 27 inches.
My questions are:
1) Do you know of a like for like replacement for the pump? They do not seem to make this model anymore.
2) Do I need a key to turn the square isolator valves above and below the pump? (They are square)
3) Do I need to drain the system to fit the immersion heater element? Will the tank be full to the top?
4) Is an immersion heater needed now or is a simple blanking plate better?
Any help much appreciated.

 

[D_Hailsham]

Suitable pumps are (in price order)

Grundfos UPS2 15-50/60; Grundfos Alpha 2L 15-50/60; Grundfos Alpha 2 15-50/60

You don't need to drain the system. Just drain enough HW (say 20 litres) from the cylinder so the water level is below the Immersion opening.

An immersion is always useful as it provides HW when the boiler packs up.