There's is a car park (pay and display) just above the lake, and is roughly at the finish line. Out the gates, turn right and you are on the bike course.
Access to lake, isn't permitted for general swimming.
As to waiting for him at the top of the hills, you'll be fine for the first half of the loop, which is relatively flat and quick, but take some warm clothes for the second half as you could be waiting a while and quite often.
Great course, deserves respect, but beware of the run. Get off the bike and then it's a hilly run, that catches most people out