Conversion to NG is not really that hard. There are 2 ways. One go on fleabay and watch for someone selling a NG manifold for your model. It is a simple swap, get a line from the grill to the house and you're done. As for the side burner you can remove the gas jet and simply enlarge it about 20%.
The other way will not allow you to ever return to running propane and needs to be done VERY carefully but is certainly not "hard". Remove the spuds (gas jets) from the 3 valves. Enlarge them about 20% (even a tiny bit more) as propane is about 25% more energy dense than NG and also runs at higher pressure than a normal gas line (11" WC vs 7" WC). In addition you need to disassemble the valves for the main burners and the 2 metering jets for low and medium settings need to be enlarged a small amount. I use precision drills in a hand type chuck to do all this. Reassemble the valves (cleaning them well of any possible metal flake and old grease) and regrease with some high temp black synthetic brake lube available in tiny packs at places like Advance or Autozone. A VERY small amount is needed so you could probably do 200 grills with the amount in that little pack. But again while effective this change is permanent you can never go back to LP again.