Yes lavender is recessive. It takes the lavender gene from both parents to produce a lavender offspring. If a bird only has one copy it carries it sight unseen. Often called split for lavender.
Lavender is totally desperate from the blue gene. They are both dilute genes but unlike blue lavender also dilutes gold. Gold, buff, red etc.
Only issue I know of with lavender is the fray feathers that sometimes show up. Some lines seem to not have the issue and others seem to not be able to get rid of it. If you look at the tails of the lavender Orpingtons when they first started coming out you'll see what I'm talking about.
If you breed a lavender to a non lavender then they'll be splits. Breed splits together and you get 25% lavender 25 non lavender or split and 50% splits.
Lavender to splits gets 50% lavender and 50 % splits. Lavender to lavender equals all lavender.
Most don't mix lavender with blues or splash because it is sometimes hard to tell light blue and splash chicks from lavender. Also people that breed blues don't like surprise lavender showing up later on.
Birds that are split or carry the lavender gene can pass it from generation to generation sight unseen forever. Then one day you happen to breed to carriers together and lavender pop out.
Lavender is also called self blue.