The lag time is something you will have to get used to; it's not a fishing skiff. You have several tons there and lots of inertia.
More rudder area will improve the reaction; but you'll still have the lag. What happens with newbies is they are not used to it so when the boat doesn't respond quickly they apply MORE rudder; then when it starts to turn it picks up momentum. Unlike a car or a small boat you do NOT leave the rudder on, as soon as the bow starts to swing you reduce the rudder to just enough to keep it turning. Take all the rudder off and maybe apply counter-rudder as you approach the new heading; otherwise all that inertia will carry you past your heading and next thing you know you're all over the river. I think you're already familiar with that...
My guess is this was Zone Man's problem.... With time you'll learn the tricks. Mainly, use as little rudder as you can, be patient and plan ahead. It's a lot like learning to ride a bicycle; once you get it you'll wonder what made it so hard.
Houseboats have their own particular problem; with the forward steering (often off-center) you have no way to "aim" the boat and it will get off-course before you notice it. My approach to that is to stick a sun-catcher on the window directly over the compass, just an inch or so above my line of sight. It gives me a reference point; a piece of tape works just as well but everyone thinks the suncatcher is just an ornament. Try it; it really works.
Maneuvering I'm not sure you'll be able to get away from having to use a lot of wheel. Some folks like a spinner knob on the wheel.
Probably, time and practice will solve most of the problems for you.
She's a tired old barge but she's paid for! http://s71.photobucket.com/alb...p;current=ef324993.pbw