Yes, vinegar can be an effective way to kill individual dandelion plants to help in the hand-removal process. However, vinegar can also kill turfgrass, so use a targeted spray.

Glyphosate and other non-selective herbicides can kill orchard grass, but they will also kill the surrounding plants. Also, not all areas allow the use of glyphosate due to its environmental impact—which the EPA describes as a "potential risk to terrestrial and aquatic plants and birds, and low toxicity to honeybees." Consider mechanical removal to target the plants specifically.

No, definitely not. Pulling weeds by hand is the single most effective way to remove them because you're eliminating the entire plant—roots and all—so it won’t have a chance to grow or spread. Setting time aside a few times per week to pull weeds can keep them at bay. If the number of weeds gets overwhelming, then you can resort to other methods.

Mowing a lawn will, unfortunately, not get rid of clover, and it may even encourage it to flourish. Let your lawn grow to a healthy height of over 3 inches and then set your mower blades no lower than this level. Higher grass will cut out the light that clover loves and discourage it from spreading.