4.5 square is the biggest prop you can use on this motor safely, we run it all the time on 2500mah 4s1p 30c packs, pulls 60 amps or so for around 850-900 watts and has been clocked at 220kmh with prof' radar gun, no guesstimation like so many funjet setups seem to come with I usually run mine with a 4.5 by 4.1 APC prop, with a 2500mah pack the funjet is light and nimble and plenty fast.

Your battery will be fine if its a high quality cell, if its a HK/HC pack then no guarantees, speed costs and you get what you pay for when it comes to electronics, batteries especially.