Harry Redknapp's men kicked off their tour of Ireland in impressive fashion with two weeks remaining until their top-flight opener against Hull City.
While Loic Remy was not named in the matchday squad, despite travelling to Ireland, Hoilett and Austin proved more than enough for the home side's defence to cope with.
Hoilett opened the scoring with a cool finish before Austin's header handed QPR a two-goal advantage at half-time.
Having been given a sterner test for much of the second half, the pair struck again late in the game to round off a positive showing ahead of Tuesday's fixture with Athlone Town.
Fielding a strong side that included captain Joey Barton and recent signing Steven Caulker, QPR began well when Austin was thwarted by Craig Hyland's smart goalkeeping.
Nedum Onuoha was then on hand to deny Perez Ortega a shot at goal for the hosts eight minutes in, with QPR taking the lead shortly after.
Hoilett made the most of Alejandro Faurlin's precise throughball to tuck home the opener after 16 minutes.
Shortly after the half-hour mark, Austin had his goal with a well-placed header that left Hyland with no chance.
Ciaran Kilduff then spurned the home side's best opportunity of the half when he was played through on goal, only to fire wide.
With only three substitutes named on the QPR bench, Redknapp unsurpisingly made no changes at the break - although Shaun Wright-Phillips and Karl Henry were subsequently given run-outs.
Both sides started the second period positively but it was the hosts who created the first real opening as Kilduff's header veered marginally off target.
QPR's quality told in the end as Hoilett and Austin both wrapped up braces in stoppage time.
