You need to get the lumps out before you process or you'll block your pump. I settle my oil in a barrel which has a floating pick up (basically hose pipe going from the bottom outlet up to a float off a toilet cistern valve). All the crud sinks to the bottom and the floating pick up draws from just under the top, so what I draw out is clean. I have a 200 micron filter between the settling tank and the processor, but it hasn't ever shown any sign of blocking so I assume the settling rather than the filter is doing the work. I have a different tap on the bottom of the barrel so that eventually I can drain off cruddy oil at the bottom and start again with a clean barrel.
The GL design is the best, but it's been improved in some ways by people on the forums and GL hasn't incorporated the best changes into his plans. Two changes that I think are important to make are 1. GL shows the Venturi horizontally just before the top entrance to the reactor. That works sometimes but not reliably. The Venturi should be mounted vertically. 2. The plumbers delight condensor isn't much good. People put a multi plate still heat exchanger before the condensor using the return air from the bottom of the condensor for the "cold" side on the heat exchanger. I made that modification myself and it did wonders for the efficiency of the condensor.
I suspect that using a heat exchanger this way is putting a patch over what was a bad design in the first place, and that you could ditch the plumbers delight condensor altogether and just use the heat exchanger as a condensor with the cooling water going through the "cold" side of the condensor. I think someone on here uses two heat exchangers, one to reheat the return air in the vapour circuit and one as a condensor. Basically I don't think the plumbers delight condensor is up to the job so I'd recommend you research around how people have improved that side of things.
If you do decide to use a heat exchanger, find yourself one with threaded ports so that you can connect it to your pipe work with threaded to compression fittings (assuming you are using copper pipe). Some Worcester Bosch units have threaded ports or failing that there used to be a German company on eBay who sold generic heat exchangers with threaded ports.
As a final point for a newbie, please take proper care with the chemicals. Methanol is nasty stuff. They're not kidding with the warnings they put on it. Same goes for Kaoh.