Weights isn't an issue with a HSF (CPU fan). they are all designed to work with the motherboard allowing it to stay in place and not damage any components.
This is because most coolers have what are called bards that go through the back of the motherboard through mounting holes and the barb once through the mounting hole will expand and stop the cooler coming out.
Doing so allows you to mount any cooler in most positions without any problems. the main issue people look for is usually the mounting method. Some can take large amounts of time to install and others are fussy about were and how they are attached.
For an LGA CPU I would recommend a Titsn Fenrir TTC-NK85TZ. It provides exceptional cooling for an LGA775 chipset and is fairly easy to mount. . Most can be fairly noisy but using a simple program like Speed fan will allow you to reduce the speed of the fan and therefore the noise levels.
As for your memory most manufacturers have a memory tester on their website that will allow you to check the compatibility of memory modules with your motherboard.
for example the Corsair website HERE
allows you to select your Product type and then select your motherboard. Then it will fidn the most sauitable memory for your board.