'Vox,
Good idea swapping to more streetable tires if you're mostly riding on pavment. I gained ~1.5-2mph average speed when I swapped my aggressive knobbies for a more pavement-compatible alternative from Kenda. I loved them until I got the new ride, which they don't fit.
When it comes to tubes or tubeless, you have to have special tubeless tires (maybe rims, too? Not sure) for tubeless. I understand you can run a tube in a tubeless tire in a pinch, but not the other way around. I'm sure others have more info - anyone?
I'm with Poolie re: keeping a spare tube around the house, at least. It's VERY easy to puncture your tubes while mounting tires when you're just learning, and killing one tube without an available spare is far from happy-making, especially if you're mounting the tires preparatory to going out for a ride ;-)
Also, since I can't run Slime anymore (Presta valve issue), I actually take 2 spare tubes on rides - I find it's faster and easier to swap a punctured tube trail-side than it is to find and patch the hole. Patching happens @ home if possible. I still carry a patch kit, but appreciate not needing it trailside. The weight of the tubes pays off in convenience when/if needed. Not the right answer for everyone, though.