Ive done the same. Riding mower and motorcycle was great. All the vibration and bumps. I too got soaked and had to pull one off. Intense!!!!
Start with the nJoy Large, don't bother with the medium it's on the small size and doesn't like to stay put.
Depends, I like something large in my ass so I like the ones that are more round with a thin and then flared base. Stays in much better and gives me a full feeling. About the size of a tennis ball. Also have a inflatable one which is good if you are not sure about your limits. Enjoy!
As much as I'd like to yes, I have to say no. I'm too used to wearing one to have a semi all the time, but I still love the feel of the plug so I wear it as often as I can.