Reaper + Focusrite 2i2 + Mackie ProFX12 Compatibility issue

I am having trouble recording live drums using Reaper with Focusrite 2i2 and a Mackie ProFX12 board (2 mic's in each) and would really appreciate some help / advise. 1) My main issue is that I can't get Reaper to find the specific channels from each input device / Mic (i.e. I can only record a general mix, but can't record different Mic's on different channels as should be the case). I have seen online people setup recording equipment such as Mixers and select and name the different channels so that they can just change the inputs on each track to each mic, but I have never managed to get this to work (I just see channel 1 or 2). I have seen online ASIO is really good to use but I can only ever get WASAPI to work. 2) I'm also not sure if Reaper is able to cope with two different input devices simultaneously, as I would love to be able to setup all mic's as different tracks and record at the same time, to mix later, but couldn't find any online video's or guides of this being done. 3) Finally, even after setting my laptop sample rate and block size to that of the recording software (e.g. focusrite), I still get a roughly 400 ms latency which is really annoying whilst trying to record to a click track. Any ideas how I can remove or minimize this latency? Thanks all for any help you can offer Rob ps// I need this setup as I want to record Snare, Bass, and overheads and the Mackie can only export as a stereo USB output (meaning I can't run all 4 mic's through the Mackie)

Great advice 

Thanks for the advice, I will try these out tomorrow morning back in the studio and let you know if they work. Rob