There really is no exact length per se. Really depends on the travel of the suspension. Ideally you will want them a tad too long than too short. Best way to get a good length is to droop out your axle and measure. You should be able to go off of EVO’s though. Rears are usually longer as shown.
We use brake cleaner all the time and will be fine for a quick cleaning. As mentioned though, the plug gets saturated inside and most like it seeping through the pins inside.
You can completely disconnect and remove the plastic plug in the housing without removing the cover or anything inside. Can do this to give it a good cleaning and check the o-ring seal on the plastic housing.
These are a great option if you live in a state that does inspections and/or you are big on having a DOT legal wheel. With that said, I’d still suggest a true beadlock wheel, especially if you are concerned about rolling a bead. I can also say that I’ve never had or heard of anyone getting...