Welcome to the forum mate;
The tank was an impulse purchase eh; I think it will make a good home for some entertaining critters, one word of caution about impulse purchasing; saltwater impulses can often turn out bad, so study up if you want a new fish, coral or invertabrit.
The filter will get you going; I would personally not run the bio wheels, and investing in a good used skimmer as soon as possible will server you well. The heater will be okay too, one of the most important pieces of equipment you could have would be a refractometer, look on
www.aliexpress.com for one, can be ordered from there for around $19; and identicle to what stores here charge $50 bucks for.
The choice to use dry/live mixed rock is a good one, it's not let me down before.
Be patient, read lots and understand you are going to have some problems; most; if not all can be handled though educating yourself on community sites like this.
Don't take cranky people to seriously :-) it suppose to be fun after all.
Enjoy you're time here.