Question about readings and publication/submission of stories

So I'm in the interesting-to-me position of getting to be part of a series of public events here in home-state where a group of local genre writers read their work. I'm flattered to be included and having a lot of fun, but don't have much published fiction yet.  This has left me full of questions.  Do public readings affect first sale rights at all, if I read things that are still out on submission?  Is it different if it's a reading of the whole work versus a part?  I've been operating on the assumption that a recorded reading of a complete work probably uses up first publication if the recording is publicly posted, and that an unrecorded reading of a partial work is probably fine, but I'm not sure about unrecorded readings of complete unpublished work.  Should I just plan to write some things that I use just in readings, and don't try to submit for publication?