Bettas SHOULD NOT be put with guppies. Guppies have long colourful tails, and TBH, look just like a mini betta. You can't put two male bettas together, so putting a male betta and something that looks like one together isn't wise.
Not really. In fact, livebearers of any sort generally make very poor companions for Bettas. This is largely due to the bright colors inherent in livebearers.