The motherboard manual will tell you, however the "normal" setup is colour matched as you guessed. The RAM will go in with a gap, as in an empty slot between your two RAM sticks.
In terms of the dual channel, the answer is "try it and see". RAM can be really sensitive and you can't be guaranteed dual channel unless you purchase the RAM together as a dual channel kit. In that case they've been tested and confirmed to work together. If you get them separately, it might work, it might not.
Sometimes you can get different brands at completely different times and they'll run in dual channel, other times you buy two separate sticks from the same manufacturer and they won't. In my experience I've been pretty lucky (my current rig runs 4 DIMMs that were purchased across 3 transactions spanning 4 years, but they all play happily in dual channel mode). Hopefully you will be too. Try it and see. The good thing is that single channel mode won't make a massive difference in performance for you.