Yes, weeds will grow through pea gravel but you can prevent this during the installation process. Install a weed barrier underneath pea gravel and swap it out every three years to keep weeds at bay.

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.

Yes, suggesting companion planting and mulching to minimize new growth.

Crabgrass is very resilient, and homemade solutions like vinegar may not be strong enough. Typically, hand-weeding is the most effective option that doesn’t involve harmful chemicals. You can use corn-meal gluten as a natural pre-emergent herbicide, but it’s not as effective as chemical weed killers.