Not familiar with Schwalbe's sealant, but I have been using Stan's latex sealant for years in my tubeless mountain bike tires... The stuff works great, but it's not always a matter of filling it and walking away.. it can take some tweaking to get it right. A quart of Stan's sealant runs around $25, but compared to 100ml for $15, Stan's is the far more economical choice.
IF you want to use sealant inside your tubes, you will need to remove the valve, add sealant, reinstall the valve, then put the tube and tire back on the rim. Reinflate, then rotate the tire and shake it in different directions to properly coat the inside of the tube. If you do get a puncture while riding, the air flow SHOULD force any additional liquid sealant sitting in the tube to the puncture, where the air rushing through it causes the sealant to form a latex plug from the inside. thereby sealing the hole. In some cases (depending on the size of the puncture and/or the amount of air in the tube, it may still actually flat, even with the sealant. If this happens, I typically reinflate to the max allowable PSI and do some more wheel shaking to ensure the sealant gets to the hole (the added air pressure helps to force it there).
But if the hole isn't too large, it WILL seal it... Good luck.
BB