You can find a lot of answers to your questions via search function and older threads, and lots of example structures. Plus, this will make it easier for you to come up with your own structures based on what you like.
To answer more specifically, the rule of thumb is a tournament usually ends no later than 20BB total in play, because stacks are so small players will be going all-in frequently. So, for a 20k stack with 10 entries and 4 rebuys that's 280k in chips. 280k/20 = 14k. So your tournament should end around the point the blinds reach 7k/14k, which is between the 13th and 14th level of the structure above. 14th and 15th level if you add a 100-100 level. Let's say it's the 14th level for simplicity's sake. I'll assume you have 30 minutes of break time in your 5 hours, so 4h30m or 270m of play time. 270/14 is about 19 minute levels. Personally that rubs me the wrong way, so I'd round down to 18 or up to 20.
Nothing stopping you from doing 100-100, but the first blind doubling means you go from 200bb to 100bb in just 1 level, so you aren't really getting much deep play in. If you want 200bb play you're better off using 40k starting stacks. Color up whenever a chip is no longer needed to make blinds. You can wait one or two levels on a color up if it lets you color up multiple chips at the same time and you prefer to stop the game less.