Yes, you would need to take the plug out in order to go poop. Poop is a semi-solid, so it won't come out around the plug like piss, which is a liquid, does.
If you decide to wear a plug 24/7, you may want to consider doing enemas to keep your ass cleaned out. First, this allows you to be able to control when you poop each day. Secondly, it is very difficult to even fart without the plug shooting out, and keeping your ass cleaned out reduces the amount of gas you produce. I would recommend that you do several 2 quart enemas at least once a day or even twice a day.
In order to wear a butt plug comfortably, you are going to have to keep it lubed up. Anyone who has worn a butt plug for a while will tell you that it hurts when the plug gets dry, so you will probably have to remove it several times a day to clean and apply lube in order for it to be comfortable.
Depending on what you intend to do with the butt plug in, there is no difference in the results between a hollow or a solid plug with how it feels to you.
Have fun, and keep us updated as to your journey.