Help with Skoda Roomster sat nav / bluetooth stereo options (keeping parking sensors)

hi, i recently purchased a 2014 SKoda roomster and would like to update the stereo. i have been looking at posts about the vw rns 310 / 315 / 510 and vw/skoda specific kenwood head units and i am confused! 

i would like to keep the factory reversing aid and add sat nav, bluetooth, a usb port and ideally keep the factory 3.5mm aux in (with either standard equipment or a decent branded stereo,. not an ebay special :-)  ). Is this all possible? what is my easiest option? (i am getting confused,. reading posts saying it will need additional bluetooth module / dab aerial / rewiring / reprogramming via vcds?..)

thanks!