Last (maybe!) piece of advice: get some of
these. 25 Gauge is the best I've found for fine work meaning 0.4 mm pitch and 0402 passives. I use 25 Ga for everything now. For the ginormous 1206 passives you ordered you could just use a paint brush! Or a shovel!
But yes, the paste wipes away easily with a paper towel. Very easy to use. Application onto the pads is a bit of an art but with practice you'll find out what works well. You could also get some isopropyl alcohol to clean up flux residue but this is really optional.
You can also, reheat, remove soldered components, clean off the solder with a copper wick, clean the pcb with alcohol and start all over again. Or anywhere in between.