Stone chips bit of advice please

Some stone chips down the side door and on front guard

Collected some decent sized dings /chips  yesterday .
Question/s

Have fired off an email ordering colour code from dealer bottle of
paint chip
150ml $18.00 INCL P&H   reckon that is cheap

1 what preparation prior applying it when it arrives   Prepsol or the
like . Ok to use .

2 post application - what type of polish  -AFTER   2 days drying
3 The nail polish like brush that comes with touch up paint always
seems to make  repair look daggy
any other clues  on how to apply  ( such as artists air brush or
similar ?

Car is metalic mica brownie bronze type colour  (hides the dust well
but can still pick the colour out ok  against bush background)


Next bit  during winter and new ore road going in will be lots of
gravel miles to be covered
I usually spray under guards and wheel wells  underneath etc  after
steam cleaning and prepping rubberised mixture

cuts down the sand blasting effect and reduces interior noise   heaps

any other ideas re prepping vehicle  for what is  really tough  road
travel over gibber like rocks 8 mm to 16 mm
sheeting  210 ks each way  6 days a week  for 5 months  will tear up
the vehicle under parts  no end
Cheers