If it's for health reasons I would definitely say to stay away from prepackaged and processed foods, although you could probably figure that out yourself! Fritos are vegan but eating a whole bag isn't good for you!

The rice cooker will be a great friend to you, doubly so if it's one that can double as a slow-cooker. Slow-cookers are a great time-saver and there are zillions of recipes you can find for them.
As for cookbooks, I love
Veganomicon: The Ultimate Vegan Cookbook and
Isa Does It. I don't know if all the recipes in them would fit in with your schedule, but there are many that don't take much time.
Isa Does It is specifically a "weekday cookbook" and the
Veganomicon has a special marker for recipes that take less than 45 minutes. The author/co-author of these books has posted lots of recipes online if you would like to take a look at them. (
http://www.theppk.com/recipes/)
As a vegetarian who is trying to "make the switch" (albeit very slowly), my favorite foods right now are bok choy, chick peas, black beans, zucchini, lentils, onions, broccoli, sunflower seeds...there is so much to choose from! As for what I have experienced, well, as a vegetarian at least I can say that my stomach works better than ever before (I previously had a lot of stomach issues) and I feel much healthier. Don't really have anything to say for weight loss but I became a vegetarian for different reasons. I have been a vegetarian for a little over a year now, for reference.