perusing
relating to your questions, for me--
I do every position OPing-- except lying on my back. Typically I OP in the shower or while cooking, so I'm constantly looking down, turning my head, reaching for stuff-- you know. doesn't matter to me.
now-- some people say swallow a little before you OP, and this might help because you're not freaked out about swallowing oil anymore so you can just relax and pull. Personally, when it gets to the point where I feel a bunch of sludge coming up at the back of my throat, I spit and pull all that mucus out, rather than pulling the mucus out and swishing with it- or trying to manage pulling up a loogie without swallowing oil.
don't stress if you're swallowing tiny bits-- if anything this will probably encourage mucus formation which you're going to spit up anyways.
I go with avocado or macadamia nut oil because you can probably put it on your skin, swallow it with pleasure, and OP--- go with the oil that you can use several ways, which is why coconut and castor oil are my top picks (though haven't tried avocado or macadamia.)