A couple of excellent books I'd recommend for you are:
Chris White's The Cruising Multihull
, which, although getting a bit long in tooth, is an excellent book for anyone interested in multihulls.
Mike Mullen's Multihull Seamanship
is also an excellent book to get. It really details the differences between sailing a monohull and sailing a multihull.
There are a few things you do have to keep in mind when sailing a multihull that are very different than when sailing a monohull.
reefing the sails is much more important on a multihull. Unlike a monohull, a multihull can't heel much to bleed off the excess wind strength. This is why a multihull generally reefs for the wind gust speeds rather than average wind speed. When a gust hits a multihull, it can't be over-canvassed, since the monohull just heels, but the multihull can't do that.
Another thing to keep in mind is the difference in apparent wind that can come up when sailing a multihull. The difference is far greater than what you might see on a monohull. For instance, say you're on a catamaran sailing downwind in 20 knots of true wind. You might be on a broad reach and doing 14 knots. That means the apparent wind on the boat is about 6 knots or so. Now, in 6 knots of wind, you can have an awful lot of sail up and not be overpowered. Say you have the full 150% genny and mainsail up.
Now you come about to head upwind—the apparent wind jumps from 6 knots to 20 knots... and then the boat starts to move... now you're doing 14 knots upwind on close reach.... the apparent wind has jumped from 6 knots to over 30, and you've still got the full main and 150% genny up, and you're going to get into trouble really quickly if you don't reduce sail.
On a multihull, you have to think about what the true wind speed is, and how much sail you have up, long before you turn upwind. On a monohull of the same LOA as the Iroquois, you might be doing 7 knots on a beam reach, instead of 12, and have an apparent wind of 13 knots or so... and then when you turn up wind, you might make 8 knots, and have an apparent wind of 28 knots or so... or about an 110% increase in wind speed. The same conditions on the Iroquois might result in a 300% increase in wind speeds.. Just some food for thought.